Display device with a capacitive touch panel

ABSTRACT

A display device including a laminate between a display panel and a cover layer, the laminate having a viewing-side polarizing plate; a first conductive layer, a dielectric layer and a second conductive layer constituting a capacitive touch sensor; and a substrate, the first conductive layer, dielectric layer, second conductive layer, and substrate are positioned closer to the cover layer than is the viewing-side polarizing plate, the first conductive layer is formed on one surface of the substrate, the dielectric layer is formed on a surface of the first conductive layer opposite to the substrate side, the second conductive layer is formed on a surface of the dielectric layer opposite to the first conductive layer side, the substrate has an optical film with a predetermined phase difference, the viewing-side polarizing plate has a polarizing film, a slow axis of optical film intersects a transmission axis of polarizing film at predetermined angle.

TECHNICAL FIELD

This disclosure relates to a display device with a touch panel, inparticular to a display device with a capacitive touch panel.

BACKGROUND

As displays combined with input means, display devices with touch panelsare widely used in electronics, such as laptop computers, OA equipment,medical equipment, car navigation devices, portable electronic devicessuch as mobile phones, and personal digital assistants (PDAs).

Here, different types of touch panels are known, including capacitivetype, optical type, ultrasonic type, electromagnetic induction type,resistance film type, and the like. Among these, in particular,capacitive type, which detects input coordinates by monitoring changesin the electrostatic capacity between a finger tip and a conductivelayer, is becoming the mainstream of current touch panels, on par withresistance film type.

As a conventional display device with a capacitive touch panel, forexample, a liquid crystal display device is known to have: abacklight-side polarizing plate; a liquid crystal panel formed with aliquid crystal layer sandwiched between two glass base plates (a thinfilm transistor base plate and a color filter base plate); aviewing-side polarizing plate; a touch sensor unit; and a cover glasslayer, which are stacked in the stated order from the backlight sidetowards the viewing side. Additionally, the above conventional liquidcrystal display device with a capacitive touch panel may have a phasedifference film for viewing angle compensation provided between theliquid crystal panel and the viewing-side polarizing plate.

In addition, a conventional liquid crystal display device with a touchpanel proposes providing a quarter wavelength plate between aviewing-side polarizing plate and a cover glass layer such that linearlypolarized light traveling from the liquid crystal panel side through theviewing-side polarizing plate towards the cover glass layer side isconverted by the quarter wavelength plate into circularly polarizedlight or elliptically polarized light (see, for example, JP2009-169837A(PTL 1)). In this way, when a liquid crystal display device with a touchpanel is operated by an individual wearing polarized sunglasses, thedisplayed content can be visually recognized even under the condition ofso-called crossed nicols, in which a transmission axis of theviewing-side polarizing plate and a transmission axis of the polarizedsunglasses are set orthogonal to each other.

Moreover, as another conventional display device with a capacitive touchpanel, an organic EL display device is known to have: a display panelformed by an organic EL display (OLED) panel and a barrier glass layerwhich is positioned closer to the viewing side than is the OLED panel;an anti-reflective circularly polarizing plate formed by a quarterwavelength plate and a polarizing plate which is positioned closer tothe viewing side than is the quarter wavelength plate; a touch sensorunit; and a cover glass layer, which are stacked in the stated orderfrom the display panel side (light emitting side) towards the viewingside (see, for example, JP2013-41566A (PTL 2)). Such an organic ELdisplay device can prevent incident external light (natural light) beingreflected at the surface of the OLED panel (particularly the surface ofan electrode in the OLED panel) from making visual recognition of thedisplayed content difficult.

Additionally, any of the above conventional display devices withcapacitive touch panels has a touch sensor unit that is formed with, forexample, two transparent base plates, each having a conductive layerformed on a surface thereof, stacked together such that the conductivelayer of one transparent base plate face a surface of the othertransparent base plate on the side opposite where the conductive layerof the other transparent base plate is formed (see, for example,JP2013-3952A (PTL 3)).

CITATION LIST Patent Literature

PTL 1: JP2009-169837A

PTL 2: JP2013-41566A

PTL 3: JP2013-3952A

SUMMARY Technical Problem

Recently, there is increasing demand for further reduction in thethickness and weight of display devices with capacitive touch panels.

However, the above conventional display devices with capacitive touchpanels have the problem that since a touch sensor unit is formed withtwo transparent base plates, each having a conductive layer formed on asurface thereof, the thickness between the liquid crystal panel or OLEDpanel and the cover glass layer increases, which results in an increasein the thickness of the entire device.The problem of increased thickness between the liquid crystal panel orOLED panel and the cover glass layer becomes more pronounced,particularly in the case of many members being present between theliquid crystal panel or OLED panel and the cover glass layer, such aswhere, as described above, a phase difference film for viewing anglecompensation is provided, a quarter wavelength plate is provided toenable the operator to operate the display device with a tough panelthrough polarized sunglasses, an anti-reflective circularly polarizingplate is provided, and so on.

Therefore, a first object of the disclosure is to provide a displaydevice with a capacitive touch panel that is reduced in thickness.

In addition, a second object of the disclosure is to provide a displaydevice with a capacitive touch panel that can be operated by theoperator even through polarized sunglasses and is reduced in thickness.

Moreover, a third object of the disclosure is to provide a displaydevice with a capacitive touch panel that can prevent reflected light ofincident external light from making visual recognition of the displayedcontent difficult, and that is reduced in thickness.

Solution to Problem

To solve the above problem, intense study was made and the study gave anidea of forming a touch sensor, including two conductive layers and adielectric layer positioned between the conductive layers, on onesurface of an optical member (for example, a phase difference film, aquarter wavelength plate, an anti-reflective circularly polarizingplate, or the like) used in a display device with a capacitive touchpanel to eliminate the need for transparent base plates for forming theconductive layers, thereby reducing the thickness of the display devicewith a capacitive touch panel. The disclosure was made based on thisidea.

That is, to solve the aforementioned problem advantageously, accordingto a first aspect of the disclosure, there is provided a display devicewith a capacitive touch panel comprising a laminate between a displaypanel and a cover layer, the laminate having a viewing-side polarizingplate, a first conductive layer, a dielectric layer, a second conductivelayer, and a substrate, the first conductive layer, the dielectriclayer, and the second conductive layer constituting a capacitive touchsensor, wherein the first conductive layer, the dielectric layer, thesecond conductive layer, and the substrate are positioned closer to thecover layer than is the viewing-side polarizing plate, the firstconductive layer is formed on one surface of the substrate, thedielectric layer is formed on a surface of the first conductive layeropposite to the substrate side, the second conductive layer is formed ona surface of the dielectric layer opposite to the first conductive layerside, the substrate has an optical film with a phase difference of(2n−1)λ/4, where n is a positive integer, the viewing-side polarizingplate has a polarizing film, and a slow axis of the optical filmintersects a transmission axis of the polarizing film at an angle ofabout 45° as viewed in a stacking direction. In this way, by providingthe substrate closer to the cover layer than is the viewing-sidepolarizing plate, the substrate having the optical film for imparting apredetermined phase difference to light, and by setting the angle atwhich the slow axis of the optical film and the transmission axis of thepolarizing film intersect to about 45°, the display device with a touchpanel can be operated by the operator even through polarized sunglasses.In addition, when the first conductive layer, dielectric layer, andsecond conductive layer constituting the capacitive touch sensor areformed on the one surface of the substrate in the stated order, it ispossible to reduce transparent base plates for forming the conductivelayers and simplify the structure of the touch sensor, thereby reducingthe thickness between the display panel and the cover layer.

In the first aspect, “about 45°” covers angles of, for example, 45°±10°,at which linearly polarized light traveling from the display panel sidethrough the viewing-side polarizing plate towards the cover layer sidecan be converted by the optical film of the substrate into circularlypolarized light or elliptically polarized light to enable operationthrough polarized sunglasses.

Here, in the display device with a capacitive touch panel according tothe first aspect, it is preferred that the first conductive layer isformed on a surface of the substrate on the side of the cover layer, andfurthermore, it is more preferred that the polarizing film is positionedat a surface of the viewing-side polarizing plate on the side of thecover layer, and the substrate is bonded to a surface of the polarizingfilm on the side of the cover layer. In this way, the substrate can beused as a protective film for the polarizing film, which makes itpossible to eliminate the need for the cover layer-side protective filmof the polarizing film and to further reduce the thickness between thedisplay panel and the cover layer.

In addition, to solve the aforementioned problem advantageously,according to a second aspect of the disclosure, there is provided adisplay device with a capacitive touch panel comprising a laminatebetween a display panel and a cover layer, the laminate having aviewing-side polarizing plate, a first conductive layer, a dielectriclayer, a second conductive layer, and an optical compensation substrate,the first conductive layer, the dielectric layer, and the secondconductive layer constituting a capacitive touch sensor, wherein thefirst conductive layer, the dielectric layer, the second conductivelayer, and the optical compensation substrate are positioned closer tothe display panel than is the viewing-side polarizing plate, the firstconductive layer is formed on one surface of the optical compensationsubstrate, the dielectric layer is formed on a surface of the firstconductive layer opposite to the optical compensation substrate side,the second conductive layer is formed on a surface of the dielectriclayer opposite to the first conductive layer side, and the opticalcompensation substrate has a phase difference film for opticalcompensation. In this way, when the optical compensation substratehaving the phase difference film for optical compensation is providedcloser to the display panel than is the viewing-side polarizing plate,it is possible to compensate for viewing angle dependence, a lightleakage phenomenon occurring at the polarizing plate at the time ofoblique angle viewing, and the like. In addition, when the firstconductive layer, dielectric layer, and second conductive layerconstituting the capacitive touch sensor are formed on the one surfaceof the optical compensation substrate in the stated order, it ispossible to reduce transparent base plates for forming the conductivelayers and simplify the structure of the touch sensor, thereby reducingthe thickness between the display panel and the cover layer.

Here, in the display device with a capacitive touch sensor according tothe second aspect, it is preferred that the display device furthercomprises an optical film with a phase difference of (2n−1)λ/4, where nis a positive integer, between the cover layer and the viewing-sidepolarizing plate, the viewing-side polarizing plate has a polarizingfilm, and a slow axis of the optical film intersects a transmission axisof the polarizing film at an angle of about 45° as viewed in a stackingdirection. In this way, by providing the optical film for imparting apredetermined phase difference to light closer to the cover layer thanis the viewing-side polarizing plate, and by setting the angle at whichthe slow axis of the optical film and the transmission axis of thepolarizing film intersect to about 45°, the display device with a touchpanel can be operated by the operator even through polarized sunglasses.

In the second aspect, “about 45°” covers angles of, for example,45°±10°, at which linearly polarized light traveling from the displaypanel side through the viewing-side polarizing plate towards the coverlayer side can be converted by the optical film into circularlypolarized light or elliptically polarized light to enable operationthrough polarized sunglasses.

In addition, in the display device with a capacitive touch panelaccording to the second aspect, it is preferred that the firstconductive layer is formed on a surface of the optical compensationsubstrate on the side of the display panel, the viewing-side polarizingplate has a polarizing film, the polarizing film is positioned at asurface of the viewing-side polarizing plate on the side of the displaypanel, and the optical compensation substrate is bonded to a surface ofthe polarizing film on the side of the display panel. In this way, theoptical compensation substrate can be used as a protective film for thepolarizing film, which makes it possible to eliminate the need for thedisplay panel-side protective film of the polarizing film and to furtherreduce the thickness between the display panel and the cover layer.

In addition, to solve the aforementioned problem advantageously,according to a third aspect of the disclosure, there is provided adisplay device with a capacitive touch panel comprising a laminatebetween a display panel and a cover layer, the laminate having aviewing-side polarizing plate, a first conductive layer, a dielectriclayer, and a second conductive layer, the first conductive layer, thedielectric layer, and the second conductive layer constituting acapacitive touch sensor, wherein the first conductive layer is formed onone surface of the viewing-side polarizing plate, the dielectric layeris formed on a surface of the first conductive layer opposite to theviewing-side polarizing plate side, and the second conductive layer isformed on a surface of the dielectric layer opposite to the firstconductive layer side. In this way, when the first conductive layer,dielectric layer, and second conductive layer constituting thecapacitive touch sensor are formed on the one surface of theviewing-side polarizing plate in the stated order, it is possible toreduce transparent base plates for forming the conductive layers andsimplify the structure of the touch sensor, thereby reducing thethickness between the display panel and the cover layer.

Additionally, in the display device with a capacitive touch panelaccording to the above first to third aspects, the display panel ispreferably a liquid crystal panel.

In addition, to solve the aforementioned problem advantageously,according to a fourth aspect of the disclosure, there is provided adisplay device with a capacitive touch panel comprising a laminatebetween a display panel and a cover layer, the laminate having acircularly polarizing plate, a first conductive layer, a dielectriclayer, and a second conductive layer, the first conductive layer, thedielectric layer, and the second conductive layer constituting acapacitive touch sensor, wherein the circularly polarizing plateincludes a substrate and a polarizing plate, the first conductive layer,the dielectric layer, the second conductive layer, and the substrate arepositioned closer to the display panel than is the polarizing plate, thefirst conductive layer is formed on one surface of the substrate, thedielectric layer is formed on a surface of the first conductive layeropposite to the substrate side, the second conductive layer is formed ona surface of the dielectric layer opposite to the first conductive layerside, the substrate has an optical film with a phase difference of λ/4,the polarizing plate has a polarizing film, and a slow axis of theoptical film intersects a transmission axis of the polarizing film at anangle of about 45° as viewed in a stacking direction. In this way, bysetting the angle at which the slow axis of the optical film intersectsthe transmission axis of the polarizing film to about 45°, a circularlypolarizing plate can be formed by the polarizing plate and the substratehaving the optical film with a phase difference of λ/4. Additionally,when the circularly polarizing plate comprising, at a position closer tothe display panel than is the polarizing plate, the substrate having theoptical film for imparting a phase difference of λ/4 to light isprovided between the display panel and the cover layer, it is possibleto prevent reflected light of incident external light from making visualrecognition of the displayed content difficult. In addition, when thefirst conductive layer, dielectric layer, and second conductive layerconstituting the capacitive touch sensor are formed on the one surfaceof the substrate in the stated order, it is possible to reducetransparent base plates for forming the conductive layers and simplifythe structure of the touch sensor, thereby reducing the thicknessbetween the display panel and the cover layer. In the fourth aspect,“about 45°” covers angles of, for example, 45°±5°, at which it ispossible to prevent reflected light of incident external light frommaking visual recognition of the displayed content difficult. Inaddition, the polarizing plate and substrate constituting the circularlypolarizing plate may be arranged apart from each other in the stackingdirection, or another member may be interposed between the polarizingplate and the substrate.

Here, in the display device with a capacitive touch panel according tothe fourth aspect, it is preferred that the first conductive layer isformed on a surface of the substrate on the side of the display panel,and furthermore, it is more preferred that the polarizing film ispositioned at a surface of the polarizing plate on the side of thedisplay panel, and the substrate is bonded to a surface of thepolarizing film on the side of the display panel. In this way, thesubstrate can be used as a protective film for the polarizing film,which makes it possible to eliminate the need for the display panel-sideprotective film of the polarizing film and to further reduce thethickness between the display panel and the cover layer.

In addition, to solve the aforementioned problem advantageously,according to a fifth aspect of the disclosure, there is provided adisplay device with a capacitive touch panel comprising a laminatebetween a display panel and a cover layer, the laminate having acircularly polarizing plate, a first conductive layer, a dielectriclayer, and a second conductive layer, the first conductive layer, thedielectric layer, and the second conductive layer constituting acapacitive touch sensor, wherein the circularly polarizing plateincludes a substrate and a polarizing plate, the substrate is positionedcloser to the display panel than is the polarizing plate, the firstconductive layer is formed on one surface of the polarizing plate, thedielectric layer is formed on a surface of the first conductive layeropposite to the polarizing plate side, the second conductive layer isformed on a surface of the dielectric layer opposite to the firstconductive layer side, the substrate has an optical film with a phasedifference of λ/4, the polarizing plate has a polarizing film, and aslow axis of the optical film intersects a transmission axis of thepolarizing film at an angle of about 45° as viewed in a stackingdirection. In this way, by setting the angle at which the slow axis ofthe optical film intersects the transmission axis of the polarizing filmto about 45°, a circularly polarizing plate can be formed by thepolarizing plate and the substrate having the optical film with a phasedifference of λ/4. Additionally, when the circularly polarizing platecomprising, at a position closer to the display panel than is thepolarizing plate, the substrate having the optical film for imparting aphase difference of λ/4 to light is provided between the display paneland the cover layer, it is possible to prevent reflected light ofincident external light from making visual recognition of the displayedcontent difficult. In addition, when the first conductive layer,dielectric layer, and second conductive layer constituting thecapacitive touch sensor are formed on the one surface of the polarizingplate in the stated order, it is possible to reduce transparent baseplates for forming the conductive layers and simplify the structure ofthe touch sensor, thereby reducing the thickness between the displaypanel and the cover layer.

In the fifth aspect, “about 45°” covers angles of, for example, 45°±5°,at which it is possible to prevent reflected light of incident externallight from making visual recognition of the displayed content difficult.In addition, the polarizing plate and substrate constituting thecircularly polarizing plate may be arranged apart from each other in thestacking direction, or another member may be interposed between thepolarizing plate and the substrate.

Here, in the display device with a capacitive touch panel according tothe fifth aspect, it is preferred that the first conductive layer isformed on a surface of the polarizing plate on the side of the coverlayer, and furthermore, it is more preferred that the polarizing film ispositioned at a surface of the polarizing plate on the side of thedisplay panel, and the substrate is bonded to a surface of thepolarizing film on the side of the display panel. In this way, thesubstrate can be used as a protective film for the polarizing film,which makes it possible to eliminate the need for the display panel-sideprotective film of the polarizing film and to further reduce thethickness between the display panel and the cover layer.

Additionally, in the display device with a capacitive touch panelaccording to the above fourth and fifth aspects, it is preferred thatthe optical film has reverse wavelength dispersion characteristics. Inthis way, the phase difference imparted to light incident on the opticalfilm increases in absolute value with increasing wavelength of the lightand decreases in absolute value with decreasing wavelength of the light,and therefore desirable polarization characteristics can be obtainedover a wide wavelength range, which makes it possible to convertlinearly polarized light into circularly polarized light in a favorablemanner.

In addition, to solve the aforementioned problem advantageously,according to a sixth aspect of the disclosure, there is provided adisplay device with a capacitive touch panel comprising a laminatebetween a display panel and a cover layer, the laminate having acircularly polarizing plate, a first conductive layer, a dielectriclayer, and a second conductive layer, the first conductive layer, thedielectric layer, and the second conductive layer constituting acapacitive touch sensor, wherein the circularly polarizing plateincludes a polarizing plate, a substrate positioned closer to thedisplay panel than is the polarizing plate, and a polarizing plate-sidesubstrate positioned between the polarizing plate and the substrate, thepolarizing plate has a polarizing film, the substrate has an opticalfilm with a phase difference of λ/4, the polarizing plate-side substratehas another optical film with a phase difference of λ/2, the firstconductive layer is formed on one surface of a conductive-layer basemember, the dielectric layer is formed on a surface of the firstconductive layer opposite to the conductive-layer base member side, thesecond conductive layer is formed on a surface of the dielectric layeropposite to the first conductive layer side, and the conductive-layerbase member is the substrate, the polarizing plate-side substrate, orthe polarizing plate. In this way, when the circularly polarizing platecomprising the polarizing plate, the polarizing plate-side substratehaving said another optical film for imparting a phase difference of λ/2to light, and the substrate having the optical film for imparting aphase difference of λ/4 to light is provided between the display paneland the cover layer, it is possible to prevent reflected light ofincident external light from making visual recognition of the displayedcontent difficult. In addition, when the first conductive layer,dielectric layer, and second conductive layer constituting thecapacitive touch sensor are formed on the one surface of theconductive-layer base member, which is selected from the substrate, thepolarizing plate-side substrate, or the polarizing plate, in the statedorder, it is possible to reduce transparent base plates for forming theconductive layers and simplify the structure of the touch sensor,thereby reducing the thickness between the display panel and the coverlayer.

As used herein, the “circularly polarizing plate” refers to a memberthat is capable of converting light incident from the cover layer sidetowards the display panel side into linearly polarized light, thenconverting the linearly polarized light into circularly polarized light,and further converting reverse circularly polarized light resulting fromthe circularly polarized light reflected at the display panel, intoanother linearly polarized light orthogonal to the linearly polarizedlight, to thereby prevent transmission of the reflected light into thecover layer side. Accordingly, in the sixth aspect, it suffices toarrange the substrate, the polarizing plate-side substrate, and thepolarizing plate so as to form a circularly polarizing plate.Additionally, the polarizing plate, substrate, and polarizing plate-sidesubstrate constituting the circularly polarizing plate may be arrangedapart from each other in the stacking direction, or another member maybe interposed between these members.

Here, in the display device with a capacitive touch panel according tothe sixth aspect, it is preferred that the polarizing film is positionedat a surface of the polarizing plate on the side of the display panel,and the polarizing plate-side substrate is bonded to a surface of thepolarizing film on the side of the display panel. In this way, thepolarizing plate-side substrate can be used as a protective film for thepolarizing film, which makes it possible to eliminate the need for thedisplay panel-side protective film of the polarizing film and to furtherreduce the thickness between the display panel and the cover layer.

Moreover, in the display device with a capacitive touch panel accordingto the sixth aspect, it is preferred that as viewed in a stackingdirection, a slow axis of the optical film intersects a transmissionaxis of the polarizing film at an angle of about 75°, and a slow axis ofsaid another optical film intersects the transmission axis of thepolarizing film at an angle of about 15°.

In addition, in the display device with a capacitive touch panelaccording to the sixth aspect, it is preferred that as viewed in thestacking direction, the slow axis of the optical film intersects thetransmission axis of the polarizing film at an angle of about 90°, andthe slow axis of said another optical film intersects the transmissionaxis of the polarizing film at an angle of about 22.5°.In this way, it is possible to form a so-called wideband quarterwavelength plate by using the optical film and said another opticalfilm, to yield desired polarization characteristics in a wide wavelengthrange, and to convert linearly polarized light into circularly polarizedlight favorably. Therefore, it is possible to prevent reflected light ofincident external light from making visual recognition of the displayedcontent difficult.In the sixth aspect, “about 75°” and “about 15°” cover angles of, forexample, “75°±5°” and “15°±5°”, respectively, at which a widebandquarter wavelength plate can be formed to prevent reflected light ofincident external light from making visual recognition of the displayedcontent difficult. Additionally, “about 75°” and “about 15°” representangles measured in the same direction with respect to the transmissionaxis of the polarizing film. In addition, “about 90°” and “about 22.5°”cover angles of, for example, “90°±5°” and “22.5°±5°”, respectively, atwhich a wideband quarter wavelength plate can be formed to preventreflected light of incident external light from making visualrecognition of the displayed content difficult. Additionally, “about90°” and “about 22.5°” represent angles measured in the same directionwith respect to the transmission axis of the polarizing film.

Additionally, in the display device with a capacitive touch panelaccording to the fourth to sixth aspects, the display panel preferablycomprises an organic EL display panel.

In addition, in the display device with a capacitive touch panelaccording to the first to second and fourth to sixth aspects, theoptical film and/or said another optical film is preferably an obliquelystretched film. When the optical film and/or said another optical filmis an obliquely stretched film, a laminate including the polarizingplate and the optical film and/or said another optical film can beproduced easily by a roll-to-roll process.

Moreover, in the display device with a capacitive touch panel accordingto the first to second and fourth to sixth aspects, it is preferred thatthe optical film, the phase difference film, and/or said another opticalfilm is formed from a cycloolefin polymer, polycarbonate, polyethyleneterephthalate, or triacetyl cellulose.Additionally, in the display device with a capacitive touch panelaccording to the first to sixth aspects, it is preferred that the firstconductive layer and the second conductive layer are formed by usingindium tin oxide, carbon nanotubes, or silver nanowires.

Advantageous Effect

According to the disclosure, it is possible to provide a display devicewith a capacitive touch panel that is reduced in thickness.

In particular, according to the disclosure, it is possible to provide adisplay device with a capacitive touch panel that can be operated eventhrough polarized sunglasses and is reduced in thickness. According tothe disclosure, it is also possible to provide a display device with acapacitive touch panel that can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult, and that is reduced in thickness.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIG. 1 contains cross-sectional views: (a) schematically illustrating across-sectional structure of the main part of a first display devicewith a capacitive touch panel according to the disclosure, and (b) and(c) each schematically illustrating a cross-sectional structure of themain part of a variation of the display device with a capacitive touchpanel illustrated in FIG. 1(a);

FIG. 2 contains cross-sectional views: (a) schematically illustrating across-sectional structure of the main part of a second display devicewith a capacitive touch panel according to the disclosure, and (b) and(c) each schematically illustrating a cross-sectional structure of themain part of a variation of the display device with a capacitive touchpanel illustrated in FIG. 2(a);

FIG. 3 contains cross-sectional views: (a) schematically illustrating across-sectional structure of the main part of a third display devicewith a capacitive touch panel according to the disclosure, and (b)schematically illustrating a cross-sectional structure of the main partof a variation of the display device with a capacitive touch panelillustrated in FIG. 3(a);

FIG. 4 contains cross-sectional views: (a) schematically illustrating across-sectional structure of the main part of a fourth display devicewith a capacitive touch panel according to the disclosure, and (b) and(c) each schematically illustrating a cross-sectional structure of themain part of a variation of the display device with a capacitive touchpanel illustrated in FIG. 4(a);

FIG. 5 contains cross-sectional views: (a) schematically illustrating across-sectional structure of the main part of a fifth display devicewith a capacitive touch panel according to the disclosure, and (b) and(c) each schematically illustrating a cross-sectional structure of themain part of a variation of the display device with a capacitive touchpanel illustrated in FIG. 5(a);

FIG. 6 contains cross-sectional views: (a) schematically illustrating across-sectional structure of the main part of a sixth display devicewith a capacitive touch panel according to the disclosure, and (b)schematically illustrating a cross-sectional structure of the main partof a variation of the display device with a capacitive touch panelillustrated in FIG. 6(a); and

FIG. 7 contains cross-sectional views: (a) schematically illustrating across-sectional structure of the main part of a seventh display devicewith a capacitive touch panel according to the disclosure, and (b) to(d) each schematically illustrating a cross-sectional structure of themain part of a variation of the display device with a capacitive touchpanel illustrated in FIG. 7(a).

DETAILED DESCRIPTION

Embodiments of the disclosed display device with a capacitive touchpanel will be described in detail with reference to the drawings. It isnoted that the same reference numerals indicate the same componentsthroughout the drawings. It is also noted that an additional layer orfilm may also be provided in any space between the members illustratedin the drawings within a range in which the object of the disclosure canbe achieved. Here, examples of such additional layers or films includeadhesive layers or pressure sensitive adhesive layers that are used tobond members together into a single structure. Preferred adhesive layersor pressure sensitive adhesive layers are transparent to visible lightand do not cause any unnecessary phase difference.

<Display Device with Capacitive Touch Panel (First Embodiment)>

FIG. 1(a) schematically illustrates a cross-sectional structure of themain part of a first display device with a capacitive touch panelaccording to the disclosure. It is noted here that the display devicewith a capacitive touch panel 100 illustrated in FIG. 1(a) is a devicethat has both a display function and a touch sensor function, thedisplay function for displaying image information on the screen and thetouch sensor function for detecting a position on the screen touched bythe operator and outputting it as an information signal to the outside.

The display device with a capacitive touch panel 100 comprises thefollowing members stacked in the stated order from the side from whichthe backlight is emitted (the lower side of FIG. 1(a), and this side ishereinafter referred to simply as the “backlight side”) towards the sidefrom which the operator views an image (the upper side of FIG. 1(a), andthis side is hereinafter referred to simply as the “viewing side”): abacklight-side polarizing plate 10; a liquid crystal panel as a displaypanel 20; a phase difference film 30 for optical compensation; aviewing-side polarizing plate 40; a substrate 50; a first conductivelayer 61; a dielectric layer 62; a second conductive layer 63; and acover layer 70. Additionally, in the display device with a capacitivetouch panel 100, the first conductive layer 61 is formed on one surfaceof the substrate 50 (on the cover layer 70 side), the dielectric layer62 is formed on a surface of the first conductive layer 61 opposite tothe substrate 50 side (on the cover layer 70 side), and the secondconductive layer 63 is formed on a surface of the dielectric layer 62opposite to the first conductive layer 61 side (on the cover layer 70side).

It is noted that the backlight-side polarizing plate 10, the displaypanel 20, the phase difference film 30, the viewing-side polarizingplate 40, the substrate 50 on which the first conductive layer 61, thedielectric layer 62, and the second conductive layer 63 are formed, andthe cover layer 70 may be integrated into a single structure by bondingthe members together using known means, such as providing adhesivelayers or pressure sensitive adhesive layers, performing plasmatreatment on the surfaces of members, and the like. That is, forexample, adhesive layers or pressure sensitive adhesive layers areformed in gaps in the layered structure illustrated in FIG. 1(a).

[Backlight-Side Polarizing Plate]

As the backlight-side polarizing plate 10, a known polarizing platehaving a polarizing film, for example, a polarizing plate formed with apolarizing film sandwiched between two protective films may be used.Additionally, the backlight-side polarizing plate 10 is arranged so thata transmission axis of the polarizing film of the backlight-sidepolarizing plate 10 and a transmission axis of a polarizing film 42 ofthe viewing-side polarizing plate 40 as detailed below are setorthogonal to each other as viewed in the stacking direction (thevertical direction in FIG. 1 (a)), and enables images to be displayed byuse of the liquid crystal panel as the display panel 20.

[Display Panel (Liquid Crystal Panel)]

The liquid crystal panel as the display panel 20 may be a liquid crystalpanel that is formed with a liquid crystal layer sandwiched between twobase plates, for example, with a liquid crystal layer 22 sandwichedbetween a thin film transistor base plate 21 positioned on the backlightside and a color filter base plate 23 positioned on the viewing side.Additionally, in the display device with a capacitive touch panel 100,the liquid crystal layer 22 of the liquid crystal panel, which isarranged between the backlight-side polarizing plate 10 and theviewing-side polarizing plate 40, is energized to present a desiredimage to the operator.It is noted that as the thin film transistor base plate 21 and the colorfilter base plate 23, known base plates may be used. In addition, as theliquid crystal layer 22, a known liquid crystal layer may be used. It isnoted that the display panel 20 which may be used in the display devicewith a capacitive touch panel disclosed herein is not limited to theliquid crystal panel with the aforementioned structure.

[Phase Difference Film]

The phase difference film 30 is an optical compensation film whichcompensates for viewing angle dependence of the liquid crystal layer 22,a light leakage phenomenon occurring at the polarizing plates 10, 40 atthe time of oblique angle viewing, and the like to thereby improveviewing angle characteristics of the display device with a capacitivetouch panel 100.Additionally, as the phase difference film 30, for example, a knownvertical uniaxial stretched film, a known horizontal uniaxial stretchedfilm, a known vertical and horizontal biaxial stretched film, or a phasedifference film obtained by polymerizing a liquid crystalline compoundmay be used. Specifically, the phase difference film 30 is notparticularly limited, and examples thereof include a film that isobtained by uniaxially or biaxially stretching a thermoplastic resinfilm produced by forming a thermoplastic resin such as a cycloolefinpolymer into a film by a known method. Additionally, examples ofcommercially available thermoplastic resin films include “Essina” and“SCA40” (manufactured by Sekisui Chemical Co., Ltd.), “ZEONOR Film”(manufactured by Zeon Corporation), and “ARTON FILM” (manufactured byJSR Corporation), all of which are trade names.

It is noted that hard coat layers or optical functional layers may beformed on both surfaces of the phase difference film 30, as is the casewith the substrate 50 as detailed below.

In addition, the phase difference film 30 may be arranged so that a slowaxis of the phase difference film 30 and the transmission axis of thepolarizing film of each of the polarizing plates 10, 40 are, forexample, parallel or orthogonal to each other as viewed in the stackingdirection.

[Viewing-Side Polarizing Plate]

The viewing-side polarizing plate 40 is not particularly limited, and anexample thereof may be a polarizing plate 40 that is formed with thepolarizing film 42 sandwiched between two protective films(backlight-side protective film 41 and cover layer-side protective film43).

[Substrate with Optical Film]

The substrate 50 having the first conductive layer 61 formed on onesurface thereof in the stacking direction (on the cover layer 70 side inFIG. 1(a)) comprises an optical film 52 with a phase difference of(2n−1)λ/4, where n is a positive integer, and hard coat layers 51, 53formed on both surfaces of the optical film 52. It is noted that theoptical film 52 of the substrate 50 is arranged so that a slow axis ofthe optical film 52 and the transmission axis of the polarizing film 42of the viewing-side polarizing plate 40 intersect at a predeterminedangle as viewed in the stacking direction.

In this case, “a predetermined angle” refers to an angle at whichlinearly polarized light traveling from the side of the liquid crystalpanel as the display panel 20 through the viewing-side polarizing plate40 towards the side of the cover layer 70 can be converted intocircularly polarized light or elliptically polarized light to enable theoperator to visually recognize the displayed content even throughpolarized sunglasses. Specifically, the predetermined angle is about45°, which more specifically covers angles of 45°±10°, preferably45°±3°, more preferably 45°±1°, and even more preferably 45°±0.3°.

In addition, the phrase “with a phase difference of (2n−1)λ/4, where nis a positive integer,” indicates that the phase difference (retardationRe) to be applied to light transmitted through the optical film 52 inthe stacking direction is about (2n−1)/4 times the wavelength λ of thelight, where n is a positive integer, which is preferably 1.Specifically, in the case where the transmitted light has a wavelengthrange from 400 nm to 700 nm, and when Re is about (2n−1)/4 times thewavelength λ, it is meant that Re is in the range of (2n−1)λ/4±65 nm,preferably in the range of (2n−1)λ/4±30 nm, and more preferably in therange of (2n−1)λ/4±10 nm. It is noted that Re is the retardation in thein-plane direction represented by the equation Re=(nx−ny)×d, where nx isthe refractive index in the film plane in the slow axis direction, ny isthe refractive index in a direction orthogonal, in the film plane, tothe slow axis in the film plane, and d is the thickness of the opticalfilm 52.

[[Optical Film]]

As the optical film 52, it is possible to use a film subjected toorientation treatment that is obtained by forming a thermoplastic resininto a film and stretching the film.

Here, a thermoplastic resin may be stretched by any known stretchingmethod, yet a preferred method is oblique stretching. The reason is asdescribed below. Although the optical film 52 needs to be stacked suchthat the slow axis of the optical film 52 and the transmission axis ofthe polarizing film 42 of the viewing-side polarizing plate 40 intersectat a predetermined angle, a stretched film subjected to generalstretching treatment (vertical stretching treatment or horizontalstretching treatment) has an optical axis oriented in a direction eitherparallel or orthogonal to the width direction of the film. Accordingly,to stack the general stretched film and the polarizing film one on topof the other at a predetermined angle, the stretched film needs to becut at an angle into a sheet of material. An obliquely stretched film,however, has an optical axis oriented in a direction inclined at anangle with respect to the width direction of the film. Accordingly, whenan obliquely stretched film is used as the optical film 52, a laminateincluding the viewing-side polarizing plate 40 and the optical film 52can be produced easily by a roll-to-roll process. It is noted that inthe case of producing a laminate including the viewing-side polarizingplate 40 and the optical film 52 by a roll-to-roll process, it sufficesto adjust the orientation angle of the obliquely stretched film used asthe optical film 52 such that the slow axis of the optical film 52 andthe transmission axis of the polarizing film 42 intersect at theaforementioned predetermined angle in the resulting laminate.

Methods for use in the oblique stretching may include those described inJPS50-83482A, JPH2-113920A, JPH3-182701A, JP2000-9912A, JP2002-86554A,JP2002-22944A, and the like. The stretching machine used for obliquestretching is not particularly limited, and a possible stretchingmachine is a conventionally known tenter-type stretching machine.Although there are different types of tenter-type stretching machinesincluding horizontal uniaxial stretching machines and simultaneousbiaxial stretching machines, the stretching machine used is not limitedto a particular type, but rather may be selected from a variety ofstretching machines as long as it allows for continuous obliquestretching of a long film.

In addition, the temperature at which the thermoplastic resin issubjected to oblique stretching is preferably in the range of Tg−30° C.to Tg+60° C. and more preferably in the range of Tg−10° C. to Tg+50° C.,where Tg is the glass-transition temperature of the thermoplastic resin.In addition, the stretching ratio is normally from 1.01 times to 30times, preferably from 1.01 times to 10 times, and more preferably from1.01 times to 5 times.

Examples of the thermoplastic resins which can be used to form theoptical film 52 include, but are not particularly limited to,cycloolefin polymers, polycarbonate, polyarylate, polyethyleneterephthalate, triacetyl cellulose, polysulfone, polyethersulfone,polyphenylene sulfide, polyimide, polyamide imide, polyethylene,polypropylene, polyvinyl chloride, polystyrene, polyolefin, polyvinylalcohol, and polyvinyl chloride-polymethyl methacrylate. Among these,preferred are cycloolefin polymers, polycarbonate, polyethyleneterephthalate, and triacetyl cellulose, more preferred are cycloolefinpolymers, and particularly preferred are cycloolefin polymers without apolar group such as an amino group, a carboxyl group, and a hydroxylgroup.

Examples of cycloolefin polymers may include norbornene-based resins,monocyclic olefin-based resins, cyclic conjugated diene-based resins,vinyl alicyclic hydrocarbon-based resins, and hydrides thereof. Amongthese, norbornene-based resins are suitably used because of their goodtransparency and good formability.

Examples of norbornene-based resins may include: a ring-opened polymerof a monomer with norbornene structure, a ring-opened copolymer of amonomer with norbornene structure and another monomer, and hydridesthereof; and an addition polymer of a monomer with norbornene structure,an addition copolymer of a monomer with norbornene structure and anothermonomer, and hydrides thereof.

Examples of commercially available cycloolefin polymers include “Topas”(manufactured by Ticona GmbH), “ARTON” (manufactured by JSRCorporation), “ZEONOR” and “ZEONEX” (manufactured by Zeon Corporation),“APEL” (manufactured by Mitsui Chemicals, Inc.), all of which are tradenames. By forming such a cycloolefin-based resin into a film, theoptical film 52 made from a thermoplastic resin can be obtained. Forfilm formation, a known film formation method is appropriately used,such as a solvent casting method and a melt extrusion method. Inaddition, cycloolefin-based resin films obtained by a film formationmethod are also commercially available, and examples thereof include“Essina” and “SCA40” (manufactured by Sekisui Chemical Co., Ltd.),“ZEONOR Film” (manufactured by Zeon Corporation), and “ARTON FILM”(manufactured by JSR Corporation), all of which are trade names. Athermoplastic resin film before stretching is generally a longunstretched film. In this context, a “long” film indicates a film havinga length of at least about 5 times or more, preferably 10 times or more,the width of the film, and specifically a film having a length longenough for the film to be wound into a roll for storage ortransportation.

The aforementioned thermoplastic resin has a glass-transitiontemperature of preferably 80° C. or higher, and more preferably from100° C. to 250° C. In addition, the photoelastic coefficient of thethermoplastic resin is, in absolute value, preferably 10×10⁻¹² Pa⁻¹ orless, more preferably 7×10⁻¹² Pa⁻¹ or less, and particularly preferably4×10⁻¹² Pa⁻¹ or less. Photoelastic coefficient C is a value representedby C=Δn/σ, where Δn is birefringence and σ is stress. By using atransparent thermoplastic resin whose photoelastic coefficient fallswithin this range, it is possible to reduce variations in in-planedirection retardation Re of the optical film. Moreover, when such anoptical film is applied to a display device using a liquid crystalpanel, it is possible to suppress a phenomenon that alters the hue atedges of the display screen of the display device.

It is noted that the thermoplastic resin used to form the optical film52 may be blended with other compounding agents. The compounding agentsare not particularly limited, and examples thereof include layeredcrystal compounds; inorganic fine particles; stabilizers such asantioxidants, heat stabilizers, light stabilizers, weatheringstabilizers, ultraviolet absorbers, and near-infrared absorbers; resinmodifiers such as lubricants and plasticizers; coloring agents such asdyes and pigments; and antistatic agents. These compounding agents maybe used alone or in combination of two or more, and the blending amountthereof is properly selected within a range not to impair the object ofthe disclosure.

Examples of antioxidants include phenolic antioxidants, phosphoricantioxidants, and sulfuric antioxidants, and among these preferred arephenolic antioxidants, and particularly preferred are alkyl-substitutedphenolic antioxidants. By blending these antioxidants, it is possible toprevent coloring of the film and decrease in strength of the film due tooxidation deterioration during the film formation, without deterioratingtransparency, low water absorption properties, and the like. Theseantioxidants may be used alone or in combination of two or more, and theblending amount thereof is properly selected within a range not toimpair the object of the disclosure, yet is normally 0.001 parts by massto 5 parts by mass, and preferably 0.01 parts by mass to 1 part by mass,per 100 parts by mass of the thermoplastic resin.

Inorganic fine particles that have an average particle size of 0.7 μm to2.5 μm and a refractive index of 1.45 to 1.55 are preferred. Specificexamples thereof include clay, talc, silica, zeolite, and hydrotalcite,and among these preferred are silica, zeolite, and hydrotalcite. Theaddition amount of inorganic fine particles is not particularly limited,yet is normally 0.001 parts by mass to 10 parts by mass, and preferably0.005 parts by mass to 5 parts by mass, per 100 parts by mass of thethermoplastic resin.

Examples of lubricants include hydrocarbon-based lubricants; fattyacid-based lubricants; higher alcohol-based lubricants; fatty acidamide-based lubricants; fatty acid ester-based lubricants; and metallicsoap-based lubricants. Among these, preferred are hydrocarbon-basedlubricants, fatty acid amide-based lubricants, and fatty acidester-based lubricants. Further, of these preferred lubricants,particularly preferred are those having a melting point of 80° C. to150° C. and an acid value of 10 mg KOH/mg or lower. If the melting pointis out of the range of 80° C. to 150° C. and in addition the acid valueis greater than 10 mg KOH/mg, the haze value can increase.

Additionally, the thickness of the stretched film used as the opticalfilm 52 is, for example, suitably set in the range of approximately 5 μmto 200 μm, and is preferably from 20 μm to 100 μm. If the thickness ofthe film is excessively small, strength or retardation value can beinsufficient, while the thickness is excessively large, transparency canbe deteriorated and it can be difficult to obtain a desired retardationvalue.

In addition, for the stretched film used as the optical film 52, it ispreferred that the content of volatile components remaining in the filmis 100 ppm by mass or less. A stretched film whose volatile componentcontent is in the above range is free from display unevenness even afterprolonged use, and presents great stability of optical properties. Here,the volatile components are substances that are contained in traceamounts in the thermoplastic resin, that have a molecular weight of 200or less, and that have a relatively low boiling point, and examplesthereof include residual monomers remained in the thermoplastic resinafter polymerization of the thermoplastic resin, and the solvent. Thecontent of volatile components may be determined by analyzing thethermoplastic resin with gas chromatography.

Examples of methods of obtaining a stretched film having a volatilecomponent content of 100 ppm by mass or less include: (a) performingoblique stretching of an unstretched film having a volatile componentcontent of 100 ppm by mass or less; and (b) performing obliquestretching of an unstretched film having a volatile component content ofmore than 100 ppm by mass, and drying the film during or after theoblique stretching to reduce the volatile component content. Amongthese, the method (a) is preferred for obtaining a stretched film with alower volatile component content. In the method (a), to obtain anunstretched film having a volatile component content of 100 ppm by massor less, it is preferred to perform melt extrusion of a resin having avolatile component content of 100 ppm by mass or less.

Additionally, the stretched film used as the optical film 52 preferablyhas a saturated water absorption of 0.01 mass % or less, and morepreferably 0.007 mass % or less. If the saturated water absorptionexceeds 0.01 mass %, the stretched film may be subject to dimensionalchanges depending on the usage environment, and internal stress mayoccur. Additionally, for example, when using a reflection type liquidcrystal panel as the display panel 20, display unevenness can occur,such as partial lightening of a black presentation (assuming a whitishappearance). By contrast, a stretched film whose saturated waterabsorption is in the above range is free from display unevenness evenafter prolonged use, and presents great stability of optical properties.

As used herein, the “saturated water absorption” may be measuredfollowing ASTM D570. In addition, the saturated water absorption of thestretched film may be adjusted by changing, for example, the type of thethermoplastic resin used in the formation of the film.

Also, the relative permittivity of the stretched film used as theoptical film 52 is preferably 2 or more and preferably 5 or less, andparticularly preferably 2.5 or less.

As used herein, the “relative permittivity” may be measured inaccordance with ASTM D150.

[[Hard Coat Layer]]

The hard coat layers 51, 53 formed on both surfaces of the optical film52 are for preventing damage to and curling of the optical film 52. Asthe material used in the formation of the hard coat layers 51, 53, amaterial that shows a hardness of “HB” or higher in the pencil hardnesstest prescribed in JIS K5700 is suitable. Examples of such materialsinclude: hard coat layer-forming organic materials such as organicsilicone-based, melamine-based, epoxy-based, acrylate-based, andpolyfunctional (meth)acrylic-based compounds; and hard coatlayer-forming inorganic materials such as silicon dioxide. Among these,(meth)acrylate-based compounds and polyfunctional (meth)acrylic-basedcompounds are preferably used as the hard coat layer-forming material inview of their good adhesive strength and excellent productivity. As usedherein, “(meth)acrylate” refers to acrylate and/or methacrylate, and“(meth)acrylic” refers to acrylic and/or methacrylic.

Examples of (meth)acrylates include those having one polymerizableunsaturated group per molecule, those having two polymerizableunsaturated groups per molecule, those having three or morepolymerizable unsaturated groups per molecule, and (meth)acrylateoligomers containing three or more polymerizable unsaturated groups permolecule. The (meth)acrylates may be used alone or in combination of twoor more.

The method of forming the hard coat layers is not particularly limited.The hard coat layers are formed by: coating a coating liquid includingthe hard coat layer-forming material on the optical film 52 by a knownmethod, such as a dipping method, a spray method, a slide coatingmethod, a bar coating method, a roll coater method, a die coater method,a gravure coater method, and a screen printing method; removing thesolvent by drying in air or in a nitrogen atmosphere or the like; andsubsequently, either applying thereon an acrylic-based hard coat layermaterial and irradiating it with ultraviolet light, electron beam, orthe like so as to be cured by crosslinking, or applying thereon asilicone-based, melamine-based, or epoxy-based hard coat layer materialand causing it to thermoset. Since the film thickness of the coatingfilm tends to become uneven during the drying process, it is preferredto adjust and control air intake and exhaust to avoid deterioration inthe appearance of the coating film, so that the coating film becomesuniform over the entire surface. When using an ultraviolet curablematerial, the irradiation time it takes for the hard coat layer-formingmaterial after the coating to be cured by being irradiated withultraviolet light is usually in the range of 0.01 seconds to 10 seconds,and the amount of irradiation from the energy ray source is usually inthe range of 40 mJ/cm² to 1000 mJ/cm² in terms of cumulative exposurewith ultraviolet light wavelength of 365 nm. The ultraviolet lightirradiation may be performed in an inert gas such as nitrogen and argon,or in air.

It is noted that if the hard coat layers 51, 53 are provided, surfacetreatment may be applied to the stretched film used as the optical film52 for the purpose of increasing the adhesiveness to the hard coatlayers 51, 53. Examples of the surface treatment include plasmatreatment, corona treatment, alkali treatment, and coating treatment. Inparticular, in the case where the optical film 52 is formed from athermoplastic norbornene-based resin, the use of corona treatment allowsfor providing strong adhesion between the optical film 52 formed fromthe above thermoplastic norbornene-based resin and the hard coat layers51, 53. As a corona treatment condition, the amount of irradiation ofcorona discharge electron is preferably 1 W/m²/min to 1000 W/m²/min. Thecontact angle with water of the optical film 52 after the above coronatreatment is preferably from 10° to 50°. In addition, coating with thecoating liquid including the hard coat layer-forming material may beperformed immediately after the corona treatment or afterneutralization. For better appearance of the hard coat layers 51, 53,however, the coating is preferably performed after neutralization.

The hard coat layers 51, 53 formed on the optical film 52 normally havean average thickness of 0.5 μm or more and 30 μm or less, and preferably2 μm or more and 15 μm or less. If the hard coat layers 51, 53 areincreased in thickness excessively out of this range, this may cause aproblem with visibility, while if the hard coat layers 51, 53 arereduced in thickness excessively, this may result in poor scratchresistance.

The haze of the hard coat layers 51, 53 is 0.5% or less, and preferably0.3% or less. By setting such haze values, the hard coat layers 51, 53can be used suitably in the display device with a touch panel 100.

It is noted that to the hard coat layer-forming material may be added,without departing from the spirit of the disclosure, organic particles,inorganic particles, a photosensitizer, a polymerization inhibitor, apolymerization initiation aid, a leveling agent, a wettability improvingagent, a surfactant, a plasticizer, an ultraviolet absorber, anantioxidant, an antistatic agent, a silane coupling agent, and the like.

It is noted that in the display device with a capacitive touch panelaccording to the disclosure, the substrate 50 may not have the hard coatlayers 51, 53, or alternatively the substrate 50 may have an opticalfunctional layer, such as an index matching layer and a low refractiveindex layer, instead of or in addition to the hard coat layers 51, 53.

[[Index Matching Layer]]

Here, an index matching layer is provided (at the interface) between theoptical film 52 of the substrate 50 and a member arranged adjacent tothe substrate 50, for example, the first conductive layer 61, for thepurpose of preventing reflection of light at the interface between thelayers caused by the difference in refractive index between the opticalfilm 52 and the first conductive layer 61. Examples of the indexmatching layer include those comprising multiple high refractive indexfilms and multiple low refractive index films that are alternatelyarranged, and resin layers comprising metals such as zirconia. Even ifthe optical film 52 and a member arranged adjacent to the substrate 50(for example, the first conductive layer 61) greatly differ inrefractive index, arranging an index matching layer makes it possible toprevent the reflectance from varying significantly at regions in thesubstrate 50, depending on whether the first conductive layer 61 isprovided or not.

[[Low Refractive Index Layer]]

A low refractive index layer is provided for the purpose of preventingreflection of light and may be provided, for example, on each of thehard coat layers 51, 53. If provided on the hard coat layers 51, 53, therespective low refractive index layers represent layers, each having arefractive index lower than that of the hard coat layers 51, 53. Therefractive index of each low refractive index layer is preferably in therange of 1.30 to 1.45, and more preferably in the range of 1.35 to 1.40,at 23° C. and wavelength of 550 nm.

As the low refractive index layers, inorganic compounds that are formedfrom SiO₂, TiO₂, NaF, Na₃AlF₆, LiF, MgF₂, CaF₂, SiO, SiO_(X), LaF₃,CeF₃, Al₂O₃, CeO₂, Nd₂O₃, Sb₂O₃, Ta₂O₅, ZrO₂, ZnO, ZnS, or the like arepreferred. In addition, a mixture of an inorganic compound with anorganic compound such as an acrylic resin, a urethane resin, and asiloxane-based polymer is preferably used as the low refractive indexlayer-forming material. One example is a low refractive index layer thatis formed by applying a composition containing an ultraviolet curableresin and hollow silica particles, and irradiating with ultravioletlight. The film thickness of the low refractive index layer ispreferably 70 nm or more and 120 nm or less, and more preferably 80 nmor more and 110 nm or less. If the film thickness of the low refractiveindex layer is more than 120 nm, reflected colors are so tinged thatcolor reproducibility is lost at the time of black presentation, whichfact may reduce visibility and cause undesirable results.

[First Conductive Layer]

The first conductive layer 61 is formed on one surface (on the coverlayer 70 side) of the substrate 50. Additionally, the first conductivelayer 61 forms a capacitive touch sensor, in conjunction with the secondconductive layer 63 positioned apart in the stacking direction acrossthe dielectric layer 62.

Here, the first conductive layer 61 may be any layer as long as it hastransmittance in the visible light region and has conductivity, and maybe formed by using any suitable material including, but not particularlylimited to, conductive polymers; conductive pastes such as silver pasteand polymer paste; metal colloids such as gold and copper; metal oxidessuch as indium tin oxide (tin-doped indium oxide: ITO), antimony-dopedtin oxide (ATO), fluorine-doped tin oxide (FTO), aluminum-doped zincoxide (AZO), cadmium oxide, cadmium-tin oxide, titanium oxide, and zincoxide; metal compounds such as copper iodide; metals such as gold (Au),silver (Ag), platinum (Pt), and palladium (Pd); and inorganic or organicnanomaterials such as silver nanowires and carbon nanotubes (CNTs).Among these, indium tin oxide, carbon nanotubes, and silver nanowiresare preferred, and particularly preferred is indium tin oxide from alight transmittivity and durability perspective.

It is noted that when CNTs are used, any of single-walled CNTs,double-walled CNTs, triple- or higher order multi-walled CNTs may beused, yet the diameter of the CNTs used is preferably from 0.3 nm to 100nm and the length thereof is preferably from 0.1 μm to 20 μm. It isnoted that from the viewpoint of increasing transparency of conductivelayers and reducing the surface resistance, single-walled CNTs ordouble-walled CNTs of 10 nm or less in diameter and 1 μm to 10 μm inlength are preferably used. It is also preferred that the collection ofCNTs contain as few impurities as possible, such as amorphous carbon andcatalyst metal.

Additionally, the formation of the first conductive layer 61 on thesurface of the substrate 50 is not particularly limited, and may beperformed by a sputtering method, a vacuum evaporation method, a CVDmethod, an ion plating method, a sol-gel method, a coating method, orthe like.

[Dielectric Layer (Insulating Layer)]

The dielectric layer 62 is formed on one surface (on the cover layer 70side) of the first conductive layer 61. The dielectric layer 62, whichis formed from a dielectric, is positioned between the first conductivelayer 61 and the second conductive layer 63 such that an electrostaticcapacity can be formed between the first conductive layer 61 and thesecond conductive layer 63.

Here, as the dielectric layer 62, any layer may be used that is formedby using a known dielectric, for example, an acrylic-based,polyimide-based, epoxy-based, polyester-based, polyurethane-based, orpolystyrene-based material.

In addition, the formation of the dielectric layer 62 on the surface ofthe first conductive layer 61 may be performed by using a known method.

It is noted that no particular limitation is placed on the structure ormaterial of the dielectric layer 62 as long as an electrostatic capacitycan be formed between the first conductive layer 61 and the secondconductive layer 63. Thus, the dielectric layer 62 may have a single- ormulti-layer structure. In addition, the dielectric layer 62 may beformed solely from a single type of material or formed from more thanone type of material.

[Second Conductive Layer]

The second conductive layer 63 is formed on one surface (on the coverlayer 70 side) of the dielectric layer 62. Additionally, the secondconductive layer 63 forms a capacitive touch sensor, in conjunction withthe first conductive layer 61 positioned apart in the stacking directionacross the dielectric layer 62.

Additionally, the second conductive layer 63 may be formed by using thesame material as the first conductive layer 61.

In addition, the formation of the second conductive layer 63 on thesurface of the dielectric layer 62 may be performed by using the samemethod as the first conductive layer 61.

Here, the conductive layers 61, 63 constituting the capacitive touchsensor are often formed in a patterned manner. Specifically, the firstconductive layer 61 and the second conductive layer 63 may be formed ina pattern such that they form a rectilinear lattice, a wavy lattice, ora diamond-like lattice when arranged to face each other and viewed inthe stacking direction. It is noted that the wavy lattice refers to ashape having at least one curved section between intersections.

Additionally, the patterned formation of the first conductive layer 61and the second conductive layer 63 may be provided by, for example,forming on the surface of the substrate 50 a first electrode layerpattern made from ITO (first conductive layers 61), forming thereondielectric layers 62, and forming on the dielectric layers 62 a secondelectrode layer pattern made from ITO (second conductive layers 63) soas to create a matrix with the first electrode layer pattern.

It is noted that the thickness of the first conductive layer 61 and ofthe second conductive layer 63, when formed from ITO, may be, forexample, and without limitation, preferably from 10 nm to 150 nm, andmore preferably from 15 nm to 70 nm. The surface resistivity of thefirst conductive layer 61 and of the second conductive layer 63 may bepreferably, but is not particularly limited to, 100 Ω/sq to 1000 Ω/sq.

[Cover Layer]

The cover layer 70 may be formed by using a known member, for example, aplate that is made of glass or plastic and is transparent to visiblelight.

Additionally, with the display device with a capacitive touch panel 100,since the substrate 50 provided with the optical film 52 having apredetermined phase difference is arranged between the viewing-sidepolarizing plate 40 and the cover layer 70, it is possible to convertlinearly polarized light traveling through the viewing-side polarizingplate 40 towards the cover layer 70 side into circularly polarized lightor elliptically polarized light. Thus, the display device with acapacitive touch panel 100 enables the operator to visually recognizethe displayed content on the display device through polarized sunglasseseven under the condition of so-called crossed nicols, in which thetransmission axis of the polarized sunglasses worn by the operator andthe transmission axis of the polarizing film 42 of the viewing-sidepolarizing plate 40 are set orthogonal to each other

In addition, in the display device with a capacitive touch panel 100,the first conductive layer 61, the dielectric layer 62, and the secondconductive layer 63 are all formed on the substrate 50, there is no needto provide transparent base plates separately for forming the first andsecond conductive layers. Accordingly, it is possible to simplify thestructure of the touch sensor and reduce the number of members presentbetween the viewing-side polarizing plate 40 and the cover layer 70,thereby reducing the thickness between the liquid crystal panel as thedisplay panel 20 and the cover layer 70. As a result, a reduction inthickness of the display device 100 can be achieved. It is noted thatsince a conductive layer is formed on only one surface of the substrate50 in the display device 100, a conductive layer uniform in thicknesscan be formed easily as compared to the case where conductive layers areformed on both surfaces of the substrate 50.

Moreover, in the above example of the display device 100, the firstconductive layer 61, dielectric layer 62, and second conductive layer 63constituting the capacitive touch sensor are disposed between theviewing-side polarizing plate 40 and the cover layer 70. Accordingly, itis possible to maintain a sufficient distance, even in the device with areduced thickness, between the liquid crystal panel as the display panel20 and the first conductive layer 61, dielectric layer 62, and secondconductive layer 63 constituting the touch sensor, as compared to thecase where the first conductive layer 61, dielectric layer 62, andsecond conductive layer 63 are provided closer to the liquid crystalpanel than is the viewing-side polarizing plate 40. Consequently, it ispossible to suppress a decrease in sensitivity of the touch sensorcaused by the influence of electrical noise from the display panel 20side. In particular, in the display device 100, since the firstconductive layer 61, dielectric layer 62, and second conductive layer 63are formed closer to the cover layer 70 than is the substrate 50, it ispossible to maintain a sufficient distance between the display panel 20and the first conductive layer 61, dielectric layer 62, and secondconductive layer 63 constituting the touch sensor, and to sufficientlysuppress a decrease in sensitivity of the touch sensor caused by theinfluence of electrical noise from the display panel 20 side.

<Display Device with Capacitive Touch Panel (First Variation of FirstEmbodiment)>

FIG. 1(b) schematically illustrates a cross-sectional structure of themain part of a variation of the aforementioned display device with acapacitive touch panel 100.

Here, the display device with a capacitive touch panel 100A illustratedin FIG. 1(b) differs from the example of the display device with acapacitive touch panel 100 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the cover layer 70 side) of the substrate 50, but on the other        surface (on the display panel 20 side) of the substrate 50;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the display panel 20 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the display panel 20 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the        viewing-side polarizing plate 40 and the substrate 50.        The display device with a capacitive touch panel 100A has        otherwise the same features as the display device with a        capacitive touch panel 100.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 100, the display device with acapacitive touch panel 100A enables the operator to visually recognizethe displayed content even under the condition of so-called crossednicols, in which the transmission axis of the polarized sunglasses wornby the operator and the transmission axis of the polarizing film 42 ofthe viewing-side polarizing plate 40 are set orthogonal to each other.It is also possible to simplify the structure of the touch sensor andreduce the thickness between the liquid crystal panel as the displaypanel 20 and the cover layer 70. Moreover, the display device 100A canalso suppress a decrease in sensitivity of the touch sensor caused bythe influence of electrical noise from the display panel 20 side, ascompared to the case where the first conductive layer 61, dielectriclayer 62, and second conductive layer 63 are formed closer to thedisplay panel 20 than is the viewing-side polarizing plate 40. Inaddition, a conductive layer uniform in thickness can be formed easilyas compared to the case where conductive layers are formed on bothsurfaces of the substrate 50.

<Display Device with Capacitive Touch Panel (Second Variation of FirstEmbodiment)>

FIG. 1(c) schematically illustrates a cross-sectional structure of themain part of another variation of the aforementioned display device witha capacitive touch panel 100.

Here, the display device with a capacitive touch panel 100B illustratedin FIG. 1(c) differs from the example of the display device with acapacitive touch panel 100 as described previously in the followingpoints:

-   -   the viewing-side polarizing plate 40 does not have the cover        layer-side protective film 43, and the polarizing film 42 is        positioned at a surface (the upper surface in FIG. 1(c)) of the        viewing-side polarizing plate 40 on the cover layer 70 side; and    -   the substrate 50 is bonded to a surface, on the cover layer 70        side, of the polarizing film 42 of the viewing-side polarizing        plate 40.        The display device with a capacitive touch panel 100B has        otherwise the same features as the display device with a        capacitive touch panel 100.

Here, the bonding of the substrate 50 on the polarizing film 42 may beperformed by using a known adhesive layer or pressure sensitive adhesivelayer.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 100, the display device with acapacitive touch panel 100B enables the operator to visually recognizethe displayed content even under the condition of so-called crossednicols, in which the transmission axis of the polarized sunglasses wornby the operator and the transmission axis of the polarizing film 42 ofthe viewing-side polarizing plate 40 are set orthogonal to each other.It is also possible to simplify the structure of the touch sensor andreduce the thickness between the liquid crystal panel as the displaypanel 20 and the cover layer 70. Moreover, similar to the display devicewith a capacitive touch panel 100, the display device 100B allows forsufficiently suppressing a decrease in sensitivity of the touch sensorcaused by the influence of electrical noise from the display panel 20side. In addition, a conductive layer uniform in thickness can be formedeasily as compared to the case where conductive layers are formed onboth surfaces of the substrate 50.

It is noted that in the display device 100B, it is possible to cause thesubstrate 50 to function as a protective film for the polarizing film42, which may thus make the cover layer-side protective film of theviewing-side polarizing plate 40 unnecessary, thereby reducing thethickness of the viewing-side polarizing plate 40. Accordingly, it ispossible to further reduce the thickness between the display panel 20and the cover layer 70. Here, in the display device 100B, the opticalfilm 52 and the polarizing film 42 may be bonded together by using, asthe substrate 50, a substrate that does not have the hard coat layer 51on the polarizing film 42 side of the optical film 52 (namely, asubstrate having the optical film 52 positioned at a surface thereof onthe display panel 20 side). If not only the cover layer-side protectivefilm of the viewing-side polarizing plate 40, but also the hard coatlayer 51 of the substrate 50 is no longer needed, the thickness betweenthe display panel 20 and the cover layer 70 can be reduced even more.

<Display Device with Capacitive Touch Panel (Second Embodiment)>

FIG. 2(a) schematically illustrates a cross-sectional structure of themain part of a second display device with a capacitive touch panelaccording to the disclosure.

Here, the display device with a capacitive touch panel 200 illustratedin FIG. 2(a) differs from the example of the display device with acapacitive touch panel 100 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the cover layer 70 side) of the substrate 50, but on one surface        (on the cover layer 70 side) of an optical compensation        substrate formed by the phase difference film 30 for optical        compensation; and    -   the first conductive layer 61, the dielectric layer 62 formed on        a surface of the first conductive layer 61 on the cover layer 70        side, and the second conductive layer 63 formed on a surface of        the dielectric layer 62 on the cover layer 70 side are        positioned closer to the display panel 20 than is the        viewing-side polarizing plate 40, specifically between the        viewing-side polarizing plate 40 and the phase difference film        30 for optical compensation. The display device with a        capacitive touch panel 200 has otherwise the same features as        the display device with a capacitive touch panel 100.        It is noted that the second display device with a capacitive        touch panel may not have the substrate 50. In addition, the        optical compensation substrate may be a phase difference film        having a hard coat layer or an optical functional layer formed        on a surface thereof.

Here, the formation of the first conductive layer 61 on the opticalcompensation substrate formed by the phase difference film 30 may beperformed by using the same method as used in the formation of the firstconductive layer 61 in the display device with a capacitive touch panel100.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 100, the display device with acapacitive touch panel 200 has the substrate 50, and thus enables theoperator to visually recognize the displayed content even under thecondition of so-called crossed nicols, in which the transmission axis ofthe polarized sunglasses worn by the operator and the transmission axisof the polarizing film 42 of the viewing-side polarizing plate 40 areset orthogonal to each other. In addition, in the display device with acapacitive touch panel 200, the first conductive layer 61, thedielectric layer 62, and the second conductive layer 63 are all formedon the optical compensation substrate (phase difference film 30), thereis no need to provide transparent base plates separately for forming thefirst and second conductive layers. Accordingly, it is possible tocompensate, by the phase difference film 30, for viewing angledependence of the liquid crystal panel as the display panel 20, a lightleakage phenomenon occurring at the polarizing plate at the time ofoblique angle viewing, and the like, simplify the structure of the touchsensor, and reduce the number of members present between the displaypanel 20 and the cover layer 70, thereby reducing the thickness betweenthe display panel 20 and the cover layer 70. As a result, a reduction inthickness of the display device 200 can be achieved. It is noted thatsince a conductive layer is formed on only one surface of the opticalcompensation substrate (phase difference film 30) in the display device200, a conductive layer uniform in thickness can be formed easily ascompared to the case where conductive layers are formed on both surfacesof the optical compensation substrate (phase difference film 30).

It is noted that in the second display device with a capacitive touchpanel according to the disclosure, it is possible to cause the substrate50 to function as a protective film for the polarizing film 42, whichmay make the cover layer-side protective film of the viewing-sidepolarizing plate 40 unnecessary, thereby reducing the thickness of theviewing-side polarizing plate 40. That is, in the second display devicewith a capacitive touch panel, the polarizing film 42 may be positionedat a surface of the viewing-side polarizing plate 40 on the cover layer70 side, and the substrate 50 may be bonded to a surface, on the coverlayer 70 side, of the polarizing film 42 of the viewing-side polarizingplate 40, thereby further reducing the thickness between the displaypanel 20 and the cover layer 70.

<Display Device with Capacitive Touch Panel (First Variation of SecondEmbodiment)>

FIG. 2(b) schematically illustrates a cross-sectional structure of themain part of a variation of the aforementioned display device with acapacitive touch panel 200.

Here, the display device with a capacitive touch panel 200A illustratedin FIG. 2(b) differs from the example of the display device with acapacitive touch panel 200 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the cover layer 70 side) of the phase difference film 30 for        optical compensation (optical compensation substrate), but on        the other surface (on the display panel 20 side) of the phase        difference film 30;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the display panel 20 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the display panel 20 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the phase        difference film 30 and the display panel 20.        The display device with a capacitive touch panel 200A has        otherwise the same features as the display device with a        capacitive touch panel 200.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 200, the display device with acapacitive touch panel 200A enables the operator to visually recognizethe displayed content even under the condition of so-called crossednicols, in which the transmission axis of the polarized sunglasses wornby the operator and the transmission axis of the polarizing film 42 ofthe viewing-side polarizing plate 40 are set orthogonal to each other.In addition, it is possible to compensate, by the phase difference film30, for viewing angle dependence of the liquid crystal panel as thedisplay panel 20, a light leakage phenomenon occurring at the polarizingplate at the time of oblique angle viewing, and the like, and simplifythe structure of the touch sensor, thereby reducing the thicknessbetween the display panel 20 and the cover layer 70. Moreover, aconductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of theoptical compensation substrate (phase difference film 30).

<Display Device with Capacitive Touch Panel (Second Variation of SecondEmbodiment)>

FIG. 2(c) schematically illustrates a cross-sectional structure of themain part of another variation of the aforementioned display device witha capacitive touch panel 200.

Here, the display device with a capacitive touch panel 200B illustratedin FIG. 2(c) differs from the example of the display device with acapacitive touch panel 200 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the cover layer 70 side) of the phase difference film 30 for        optical compensation (optical compensation substrate), but on        the other surface (on the display panel 20 side) of the phase        difference film 30;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the display panel 20 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the display panel 20 side;    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the phase        difference film 30 and the display panel 20;    -   the viewing-side polarizing plate 40 does not have the display        panel-side protective film 41, and the polarizing film 42 is        positioned at a surface (the lower surface in FIG. 2(c)) of the        viewing-side polarizing plate 40 on the display panel 20 side;        and    -   the phase difference film 30 for optical compensation (optical        compensation substrate) is bonded to a surface, on the display        panel 20 side, of the polarizing film 42 of the viewing-side        polarizing plate 40.        The display device with a capacitive touch panel 200B has        otherwise the same features as the display device with a        capacitive touch panel 200.

Here, the bonding of the phase difference film 30 (optical compensationsubstrate) on the polarizing film 42 may be performed by using a knownadhesive layer or pressure sensitive adhesive layer.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 200, the display device with acapacitive touch panel 200B enables the operator to visually recognizethe displayed content even under the condition of so-called crossednicols, in which the transmission axis of the polarized sunglasses wornby the operator and the transmission axis of the polarizing film 42 ofthe viewing-side polarizing plate 40 are set orthogonal to each other.In addition, it is possible to compensate, by the phase difference film30, for viewing angle dependence of the liquid crystal panel as thedisplay panel 20, a light leakage phenomenon occurring at the polarizingplate at the time of oblique angle viewing, and the like, and simplifythe structure of the touch sensor, thereby reducing the thicknessbetween the display panel 20 and the cover layer 70. Moreover, aconductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of theoptical compensation substrate (phase difference film 30).

It is noted that in the display device 200B, it is possible to cause thephase difference film 30 (optical compensation substrate) to function asa protective film for the polarizing film 42, which may thus make thedisplay panel-side protective film of the viewing-side polarizing plate40 unnecessary, thereby reducing the thickness of the viewing-sidepolarizing plate 40. Accordingly, it is possible to further reduce thethickness between the display panel 20 and the cover layer 70.

<Display Device with Capacitive Touch Panel (Third Embodiment)>

FIG. 3(a) schematically illustrates a cross-sectional structure of themain part of a third display device with a capacitive touch panelaccording to the disclosure.

Here, the display device with a capacitive touch panel 300 illustratedin FIG. 3(a) differs from the example of the display device with acapacitive touch panel 100 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the cover layer 70 side) of the substrate 50, but on one surface        (on the cover layer 70 side) of the viewing-side polarizing        plate 40, specifically on a surface, on the cover layer 70 side,        of the cover layer-side protective film 43 of the viewing-side        polarizing plate 40; and    -   the first conductive layer 61, the dielectric layer 62 formed on        a surface of the first conductive layer 61 on the cover layer 70        side, and the second conductive layer 63 formed on a surface of        the dielectric layer 62 on the cover layer 70 side are        positioned between the viewing-side polarizing plate 40 and the        substrate 50.        The display device with a capacitive touch panel 300 has        otherwise the same features as the display device with a        capacitive touch panel 100.        It is noted that the third display device with a capacitive        touch panel may not have both of the substrate 50 with the        optical film 52 and the phase difference film 30, or may have        only one of the substrate 50 and the phase difference film 30.

Here, the formation of the first conductive layer 61 on the viewing-sidepolarizing plate 40 may be performed by using the same method as used inthe formation of the first conductive layer 61 in the display devicewith a capacitive touch panel 100.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 100, the display device with acapacitive touch panel 300 has the substrate 50, and thus enables theoperator to visually recognize the displayed content even under thecondition of so-called crossed nicols, in which the transmission axis ofthe polarized sunglasses worn by the operator and the transmission axisof the polarizing film 42 of the viewing-side polarizing plate 40 areset orthogonal to each other. In addition, in the display device with acapacitive touch panel 300, the first conductive layer 61, thedielectric layer 62, and the second conductive layer 63 are all formedon the viewing-side polarizing plate 40, there is no need to providetransparent base plates separately for forming the first and secondconductive layers. Accordingly, it is possible to simplify the structureof the touch sensor and reduce the number of members present between thedisplay panel 20 and the cover layer 70, thereby reducing the thicknessbetween the liquid crystal panel as the display panel 20 and the coverlayer 70. As a result, a reduction in thickness of the display device300 can be achieved. It is noted that since a conductive layer is formedon only one surface of the viewing-side polarizing plate 40 in thedisplay device 300, a conductive layer uniform in thickness can beformed easily as compared to the case where conductive layers are formedon both surfaces of the viewing-side polarizing plate 40.

Moreover, in the above example of the display device 300, the firstconductive layer 61, dielectric layer 62, and second conductive layer 63constituting the capacitive touch sensor are disposed between theviewing-side polarizing plate 40 and the cover layer 70. Accordingly, itis possible to maintain a sufficient distance, even in the device with areduced thickness, between the liquid crystal panel and the firstconductive layer 61, dielectric layer 62, and second conductive layer 63constituting the touch sensor, as compared to the case where the firstconductive layer 61, dielectric layer 62, and second conductive layer 63are provided closer to the display panel 20 than is the viewing-sidepolarizing plate 40. Consequently, it is possible to suppress a decreasein sensitivity of the touch sensor caused by the influence of electricalnoise from the display panel 20 side.

<Display Device with Capacitive Touch Panel (First Variation of ThirdEmbodiment)>

FIG. 3(b) schematically illustrates a cross-sectional structure of themain part of a variation of the aforementioned display device with acapacitive touch panel 300.

Here, the display device with a capacitive touch panel 300A illustratedin FIG. 3(b) differs from the example of the display device with acapacitive touch panel 300 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the cover layer 70 side) of the viewing-side polarizing plate        40, but on the other surface (on the display panel 20 side) of        the viewing-side polarizing plate 40, specifically on a surface,        on the display panel 20 side, of the display panel-side        protective film 41 of the viewing-side polarizing plate 40;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the display panel 20 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the display panel 20 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the        viewing-side polarizing plate 40 and the phase difference film        30.        The display device with a capacitive touch panel 300A has        otherwise the same features as the display device with a        capacitive touch panel 300.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 300, the display device with acapacitive touch panel 300A enables the operator to visually recognizethe displayed content even under the condition of so-called crossednicols, in which the transmission axis of the polarized sunglasses wornby the operator and the transmission axis of the polarizing film 42 ofthe viewing-side polarizing plate 40 are set orthogonal to each other.It is also possible to simplify the structure of the touch sensor andreduce the thickness between the liquid crystal panel as the displaypanel 20 and the cover layer 70. Moreover, a conductive layer uniform inthickness can be formed easily as compared to the case where conductivelayers are formed on both surfaces of the viewing-side polarizing plate40.

<Display Device with Capacitive Touch Panel (Fourth Embodiment)>

FIG. 4(a) schematically illustrates a cross-sectional structure of themain part of a fourth display device with a capacitive touch panelaccording to the disclosure. It is noted here that the display devicewith a capacitive touch panel 400 illustrated in FIG. 4(a) is a devicethat has both a display function and a touch sensor function, thedisplay function for displaying image information on the screen and thetouch sensor function for detecting a position on the screen touched bythe operator and outputting it as an information signal to the outside.

The display device with a capacitive touch panel 400 comprises thefollowing members stacked in the stated order from the side on which theorganic EL display (OLED) panel is arranged (the lower side of FIG.4(a), and this side is hereinafter referred to simply as the “displaypanel side”) towards the side from which the operator views an image(the upper side of FIG. 4(a), and this side is hereinafter referred tosimply as the “viewing side”); an organic EL display (OLED) panel 24 anda barrier layer 25 as a display panel 20; a second conductive layer 63;a dielectric layer 62; a first conductive layer 61; a substrate 50; apolarizing plate 40; and a cover layer 70. Additionally, in the displaydevice with a capacitive touch panel 400, the first conductive layer 61is formed on one surface (on the display panel 20 side) of the substrate50, the dielectric layer 62 is formed on a surface of the firstconductive layer 61 opposite to the substrate 50 side (on the displaypanel 20 side), and the second conductive layer 63 is formed on asurface of the dielectric layer 62 opposite to the first conductivelayer 61 side (on the display panel 20 side). In addition, in thedisplay device 400, the polarizing plate 40 and the substrate 50positioned closer to the display panel 20 than is the polarizing plate40 constitute a circularly polarizing plate.

It is noted that the display panel 20, the substrate 50 formed with thefirst conductive layer 61, dielectric layer 62, and second conductivelayer 63, the polarizing plate 40, and the cover layer 70 may beintegrated into a single structure by bonding the members together usingknown means, such as providing adhesive layers or pressure sensitiveadhesive layers, performing plasma treatment on the surfaces of members,and the like. That is, for example, adhesive layers or pressuresensitive adhesive layers are formed in gaps in the layered structureillustrated in FIG. 4(a).

[Organic EL Display (OLED) Panel]

As the organic EL display (OLED) panel 24, for example, an organic ELdisplay (OLED) panel may be used that has, on a surface of a transparentbase plate, a transparent electrode formed from a transparent electrodematerial, a light-emitting layer stacked on the transparent electrodeand made from an EL material, and a back electrode stacked on thelight-emitting layer and formed to face the transparent electrode, andthat emits light on the transparent base plate side. Additionally, inthe display device with a capacitive touch panel 400, the organic ELdisplay (OLED) panel 24 is energized to present a desired image to theoperator.It is noted that any known material may be used as the transparentelectrode, the light-emitting layer, and the back electrode. Inaddition, the display panel which may be used in the display device witha capacitive touch panel disclosed herein is not limited to the oneusing the organic EL display (OLED) panel 24 with the aforementionedstructure.

[Barrier Layer]

The barrier layer 25 positioned on the viewing side of the organic ELdisplay (OLED) panel 24 may be formed by using a known member, forexample, a plate that is made of glass or plastic and is transparent tovisible light.

[Second Conductive Layer]

The second conductive layer 63 is formed on one surface (on the displaypanel 20 side) of the dielectric layer 62. Additionally, the secondconductive layer 63 forms a capacitive touch sensor, in conjunction withthe first conductive layer 61 positioned apart in the stacking directionacross the dielectric layer 62.The second conductive layer 63 used in this case may be the same as thatused in the display device with a capacitive touch panel 100. Inaddition, the formation of the second conductive layer 63 on thedielectric layer 62 may be performed by using the same method as thedisplay device with a capacitive touch panel 100.

[Dielectric Layer (Insulating Layer)]

The dielectric layer 62 is formed on one surface (on the display panel20 side) of the first conductive layer 61. The dielectric layer 62,which is formed from a dielectric, is positioned between the firstconductive layer 61 and the second conductive layer 63 such that anelectrostatic capacity can be formed between the first conductive layer61 and the second conductive layer 63.The dielectric layer 62 used in this case may be the same as that usedin the display device with a capacitive touch panel 100. In addition,the formation of the dielectric layer 62 on the first conductive layer61 may be performed by using the same method as the display device witha capacitive touch panel 100.

[First Conductive Layer]

The first conductive layer 61 is formed on one surface (on the displaypanel 20 side) of the substrate 50. Additionally, the first conductivelayer 61 forms a capacitive touch sensor, in conjunction with the secondconductive layer 63 positioned apart in the stacking direction acrossthe dielectric layer 62.The first conductive layer 61 used in this case may be the same as thatused in the display device with a capacitive touch panel 100. Inaddition, the formation of the first conductive layer 61 on thesubstrate 50 may be performed by using the same method as the displaydevice with a capacitive touch panel 100.

[Substrate with Optical Film]

The substrate 50 has the first conductive layer 61 formed on one surfacethereof in the stacking direction (on the display panel 20 side in FIG.4(a)), and comprises an optical film 52 with a phase difference of λ/4and hard coat layers 51, 53 formed on both surfaces of the optical film52. Additionally, the optical film 52 of the substrate 50 is arranged sothat a slow axis of the optical film 52 and a transmission axis of apolarizing film 42 of the polarizing plate 40 as detailed belowintersect at a predetermined angle as viewed in the stacking direction.

In this case, “a predetermined angle” refers to an angle at which acircularly polarizing plate can be formed by the polarizing plate 40 andthe optical film 52, and it is possible to prevent reflected light ofincident external light from making visual recognition of the displayedcontent difficult. Specifically, the predetermined angle is an angle atwhich linearly polarized light traveling from the cover layer 70 sidethrough the polarizing plate 40 towards the display panel 20 side can beconverted by the optical film 52 into circularly polarized light (forexample, about 45°), and more specifically covers angles of 45°±5°,preferably 45°±3°, more preferably 45°±1°, and even more preferably45°±0.3°.

In addition, the phrase “with a phase difference of λ/4” indicates thatthe phase difference (retardation Re) to be applied to light transmittedthrough the optical film 52 in the stacking direction is about ¼ timesthe wavelength λ of the light. Specifically, in the case where thetransmitted light has a wavelength range from 400 nm to 700 nm, and whenRe is about ¼ times the wavelength λ, it is meant that Re is in therange of λ/4±65 nm, preferably in the range of λ/4±30 nm, and morepreferably in the range of λ/4±10 nm. It is noted that Re is theretardation in the in-plane direction represented by the equationRe=(nx−ny)×d, where nx is the refractive index in the film plane in theslow axis direction, ny is the refractive index in a directionorthogonal, in the film plane, to the slow axis in the film plane, and dis the thickness of the optical film 52.

[[Optical Film]]

The optical film 52 used in this case may be the same as that used inthe display device with a capacitive touch panel 100.

It is noted that the optical film 52 forming part of the circularlypolarizing plate in the display device 400 with a capacitive touch panelpreferably has reverse wavelength dispersion characteristics such thatthe phase difference imparted to light incident on the optical film iswavelength dependent, namely, the phase difference becomes larger atlong wavelength and smaller at short wavelength. In this way, the phasedifference imparted to light incident on the optical film increases inabsolute value with increasing wavelength of the light and decreases inabsolute value with decreasing wavelength of the light, and therefore,desirable polarization characteristics can be obtained over a widewavelength range and linearly polarized light can be converted intocircularly polarized light.

[[Hard Coat Layer]]

The hard coat layers 51, 53 formed on both surfaces of the optical film52 used in this case may be the same as those used in the display devicewith a capacitive touch panel 100.

As is the case with the display device with a capacitive touch panel100, the substrate 50 may not have the hard coat layers 51, 53, oralternatively the substrate 50 may have an optical functional layer,such as an index matching layer and a low refractive index layer,instead of or in addition to the hard coat layers 51, 53.

[[Index Matching Layer]]

The index matching layer used in this case may be the same as that usedin the display device with a capacitive touch panel 100.

It is noted that even if the difference in refractive index between thesubstrate 50 and the layer stacked directly on the substrate 50 (forexample, a conductive layer, an adhesive layer, or a pressure sensitiveadhesive layer) is 0.05 or more, an index matching layer may not beprovided in the absence of the influence of interfacial reflection (forexample, when the first conductive layer 61 is formed on the displaypanel 20 side of the substrate 50 forming the circularly polarizingplate).

[[Low Refractive Index Layer]]

The low refractive index layer used in this case may be the same as thatused in the display device with a capacitive touch panel 100.

[Polarizing Plate]

The polarizing plate 40 used in this case is not particularly limited,and may be the same as the viewing-side polarizing plate used in thedisplay device with a capacitive touch panel 100. A specific example ofthe polarizing plate 40 may be a polarizing plate 40 that is formed withthe polarizing film 42 sandwiched between two protective films (displaypanel-side protective film 41 and cover layer-side protective film 43).Additionally, as mentioned above, the transmission axis of thepolarizing film 42 and the slow axis of the optical film 52 of thesubstrate 50 are arranged to intersect at about 45° as viewed in thestacking direction (the vertical direction in FIG. 4(a)). It is notedthat in the case of using the substrate 50 having an obliquely stretchedfilm as the optical film 52 to produce a laminate including thepolarizing plate 40 and the substrate 50 by a roll-to-roll process, itsuffices to adjust the orientation angle of the obliquely stretched filmused as the optical film 52 such that the slow axis of the optical film52 and the transmission axis of the polarizing film 42 intersect at theaforementioned predetermined angle in the resulting laminate.

[Cover Layer]

The cover layer 70 may be formed by using a known member, for example, aplate that is made of glass or plastic and is transparent to visiblelight.

Additionally, in the display device with a capacitive touch panel 400,the circularly polarizing plate formed by the polarizing plate 40 andthe substrate 50 is arranged between the cover layer 70 and the displaypanel 20, where the polarizing plate 40 has the polarizing film 42, andthe substrate 50 has the optical film 52 with a predetermined phasedifference and being arranged at a predetermined optical axis angle.This arrangement allows for preventing reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Specifically, linearly polarized light traveling from thecover layer 70 side through the polarizing plate 40 towards the displaypanel 20 side is converted into circularly polarized light by theoptical film 52 of the substrate 50, and reverse circularly polarizedlight resulting from the circularly polarized light reflected at thedisplay panel 20 is converted into another linearly polarized lightorthogonal to the linearly polarized light by the optical film 52 of thesubstrate 50. In this way, it is possible to prevent, by the polarizingplate 40, transmission of said another linearly polarized light into thecover layer 70 side. Therefore, the display device with a capacitivetouch panel 400 enables the operator to visually recognize the displayedcontent easily without interruption by reflected light.

In addition, in the display device with a capacitive touch panel 400,the first conductive layer 61, the dielectric layer 62, and the secondconductive layer 63 are all formed on the substrate 50, there is no needto provide transparent base plates separately for forming the first andsecond conductive layers. Accordingly, it is possible to simplify thestructure of the touch sensor and reduce the number of members presentbetween the display panel 20 and the cover layer 70, thereby reducingthe thickness between the display panel 20 and the cover layer 70. As aresult, a reduction in thickness of the display device 400 can beachieved. It is noted that since a conductive layer is formed on onlyone surface of the substrate 50 in the display device 400, a conductivelayer uniform in thickness can be formed easily as compared to the casewhere conductive layers are formed on both surfaces of the substrate 50.

In the display device with a capacitive touch panel 400, since the firstconductive layer 61 is formed on the display panel 20 side of thesubstrate 50 constituting the circularly polarizing plate, an indexmatching layer may not be provided on the substrate 50.

<Display Device with Capacitive Touch Panel (First Variation of FourthEmbodiment)>

FIG. 4(b) schematically illustrates a cross-sectional structure of themain part of a variation of the aforementioned display device with acapacitive touch panel 400.

Here, the display device with a capacitive touch panel 400A illustratedin FIG. 4(b) differs from the example of the display device with acapacitive touch panel 400 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the display panel 20 side) of the substrate 50, but on the other        surface (on the cover layer 70 side) of the substrate 50;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the cover layer 70 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the cover layer 70 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the substrate        50 and the polarizing plate 40.        The display device with a capacitive touch panel 400A has        otherwise the same features as the display device with a        capacitive touch panel 400.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 400, the display device with acapacitive touch panel 400A can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel400A enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. It is also possible tosimplify the structure of the touch sensor and reduce the thicknessbetween the display panel 20 and the cover layer 70. Moreover, aconductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of thesubstrate 50.

<Display Device with Capacitive Touch Panel (Second Variation of FourthEmbodiment)>

FIG. 4(c) schematically illustrates a cross-sectional structure of themain part of another variation of the aforementioned display device witha capacitive touch panel 400.

Here, the display device with a capacitive touch panel 400B illustratedin FIG. 4(c) differs from the example of the display device with acapacitive touch panel 400 as described previously in the followingpoints:

-   -   the polarizing plate 40 does not have the display panel-side        protective film 41, and the polarizing film 42 is positioned at        a surface (the lower surface in FIG. 4(c)) of the polarizing        plate 40 on the display panel 20 side; and    -   the substrate 50 is bonded to a surface, on the display panel 20        side, of the polarizing film 42 of the polarizing plate 40.        The display device with a capacitive touch panel 400B has        otherwise the same features as the display device with a        capacitive touch panel 400.

Here, the bonding of the substrate 50 on the polarizing film 42 may beperformed by using a known adhesive layer or pressure sensitive adhesivelayer.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 400, the display device with acapacitive touch panel 400B can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel400B enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. It is also possible tosimplify the structure of the touch sensor and reduce the thicknessbetween the display panel 20 and the cover layer 70. Moreover, aconductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of thesubstrate 50.

In addition, in the display device with a capacitive touch panel 400B,since the first conductive layer 61 is formed on the display panel 20side of the substrate 50, an index matching layer may not be provided onthe substrate 50, as is the case with the aforementioned example of thedisplay device with a capacitive touch panel 400.

Moreover, in the display device 400B, it is possible to cause thesubstrate 50 to function as a protective film for the polarizing film42, which may thus make the display panel-side protective film of thepolarizing plate 40 unnecessary, thereby reducing the thickness of thepolarizing plate 40. Accordingly, it is possible to further reduce thethickness between the display panel 20 and the cover layer 70.

Here, in the display device 400B, the optical film 52 and the polarizingfilm 42 may be bonded together by using, as the substrate 50, asubstrate that does not have the hard coat layer 53 on the polarizingfilm 42 side of the optical film 52 (namely, a substrate having theoptical film 52 positioned at a surface thereof on the cover layer 70side). If not only the display panel-side protective film of thepolarizing plate 40, but also the hard coat layer 53 of the substrate 50is no longer needed, the thickness between the display panel 20 and thecover layer 70 can be reduced even more.

<Display Device with Capacitive Touch Panel (Fifth Embodiment)>

FIG. 5(a) schematically illustrates a cross-sectional structure of themain part of a fifth display device with a capacitive touch panelaccording to the disclosure.

Here, the display device with a capacitive touch panel 500 illustratedin FIG. 5(a) differs from the example of the display device with acapacitive touch panel 400 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the display panel 20 side) of the substrate 50, but on one        surface (on the display panel 20 side) of the polarizing plate        40, specifically on a surface, on the display panel 20 side, of        the display panel-side protective film 41 of the polarizing        plate 40; and    -   the first conductive layer 61, the dielectric layer 62 formed on        a surface of the first conductive layer 61 on the display panel        20 side, and the second conductive layer 63 formed on a surface        of the dielectric layer 62 on the display panel 20 side are        positioned between the polarizing plate 40 and the substrate 50.        The display device with a capacitive touch panel 500 has        otherwise the same features as the display device with a        capacitive touch panel 400.

Here, the formation of the first conductive layer 61 on the polarizingplate 40 may be performed by using the same method as used in theformation of the first conductive layer 61 in the display device with acapacitive touch panel 400.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 400, the display device with acapacitive touch panel 500 can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel500 enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. In addition, in thedisplay device with a capacitive touch panel 500, the first conductivelayer 61, the dielectric layer 62, and the second conductive layer 63are all formed on the polarizing plate 40, there is no need to providetransparent base plates separately for forming the first and secondconductive layers. Accordingly, it is possible to simplify the structureof the touch sensor and reduce the number of members present between thedisplay panel 20 and the cover layer 70, thereby reducing the thicknessbetween the display panel 20 and the cover layer 70. As a result, areduction in thickness of the display device 500 can be achieved. It isnoted that since a conductive layer is formed on only one surface of thepolarizing plate 40 in the display device 500, a conductive layeruniform in thickness can be formed easily as compared to the case whereconductive layers are formed on both surfaces of the polarizing plate40.

<Display Device with Capacitive Touch Panel (First Variation of FifthEmbodiment)>

FIG. 5(b) schematically illustrates a cross-sectional structure of themain part of a variation of the aforementioned display device with acapacitive touch panel 500.

Here, the display device with a capacitive touch panel 500A illustratedin FIG. 5(b) differs from the example of the display device with acapacitive touch panel 500 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the display panel 20 side) of the polarizing plate 40, but on        the other surface (on the cover layer 70 side) of the polarizing        plate 40, specifically on a surface, on the cover layer 70 side,        of the cover layer-side protective film 43 of the polarizing        plate 40;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the cover layer 70 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the cover layer 70 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the cover        layer 70 and the polarizing plate 40.        The display device with a capacitive touch panel 500A has        otherwise the same features as the display device with a        capacitive touch panel 500.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 500, the display device with acapacitive touch panel 500A can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel500A enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. It is also possible tosimplify the structure of the touch sensor and reduce the thicknessbetween the display panel 20 and the cover layer 70. Moreover, aconductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of thepolarizing plate 40.

Moreover, in the display device 500A, the first conductive layer 61,dielectric layer 62, and second conductive layer 63 constituting thecapacitive touch sensor are disposed between the polarizing plate 40 andthe cover layer 70. Accordingly, it is possible to maintain a sufficientdistance, even in the device with a reduced thickness, between thedisplay panel and the first conductive layer 61, dielectric layer 62,and second conductive layer 63 constituting the touch sensor, ascompared to the case where the first conductive layer 61, dielectriclayer 62, and second conductive layer 63 are provided closer to thedisplay panel 20 than is the polarizing plate 40. Consequently, it ispossible to suppress a decrease in sensitivity of the touch sensorcaused by the influence of electrical noise from the display panel 20side.

<Display Device with Capacitive Touch Panel (Second Variation of FifthEmbodiment)>

FIG. 5(c) schematically illustrates a cross-sectional structure of themain part of another variation of the aforementioned display device witha capacitive touch panel 500.

Here, the display device with a capacitive touch panel 500B illustratedin FIG. 5(c) differs from the example of the display device with acapacitive touch panel 500 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the display panel 20 side) of the polarizing plate 40, but on        the other surface (on the cover layer 70 side) of the polarizing        plate 40, specifically on a surface, on the cover layer 70 side,        of the cover layer-side protective film 43 of the polarizing        plate 40;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the cover layer 70 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the cover layer 70 side;    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the cover        layer 70 and the polarizing plate 40;    -   the polarizing plate 40 does not have the display panel-side        protective film 41, and the polarizing film 42 is positioned at        a surface (the lower surface in FIG. 5(c)) of the polarizing        plate 40 on the display panel 20 side; and    -   the substrate 50 is bonded to a surface, on the display panel 20        side, of the polarizing film 42 of the polarizing plate 40.        The display device with a capacitive touch panel 500B has        otherwise the same features as the display device with a        capacitive touch panel 500.

Here, the bonding of the substrate 50 on the polarizing film 42 may beperformed by using a known adhesive layer or pressure sensitive adhesivelayer.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 500, the display device with acapacitive touch panel 500B can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel500B enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. It is also possible tosimplify the structure of the touch sensor and reduce the thicknessbetween the display panel 20 and the cover layer 70. Moreover, aconductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of thepolarizing plate 40.

Moreover, in the display device 500B, the first conductive layer 61,dielectric layer 62, and second conductive layer 63 constituting thecapacitive touch sensor are disposed between the polarizing plate 40 andthe cover layer 70. Accordingly, it is possible to maintain a sufficientdistance, even in the device with a reduced thickness, between thedisplay panel and the first conductive layer 61, dielectric layer 62,and second conductive layer 63 constituting the touch sensor, ascompared to the case where the first conductive layer 61, dielectriclayer 62, and second conductive layer 63 are provided closer to thedisplay panel 20 than is the polarizing plate 40. Consequently, it ispossible to suppress a decrease in sensitivity of the touch sensorcaused by the influence of electrical noise from the display panel 20side.

In addition, in the display device 500B, it is possible to cause thesubstrate 50 to function as a protective film for the polarizing film42, which may thus make the display panel-side protective film of thepolarizing plate 40 unnecessary, thereby reducing the thickness of thepolarizing plate 40. Accordingly, it is possible to further reduce thethickness between the display panel 20 and the cover layer 70.

Here, in the display device 500B, the optical film 52 and the polarizingfilm 42 may be bonded together by using, as the substrate 50, asubstrate that does not have the hard coat layer 53 on the polarizingfilm 42 side of the optical film 52 (namely, a substrate having theoptical film 52 positioned at a surface thereof on the cover layer 70side). If not only the display panel-side protective film of thepolarizing plate 40, but also the hard coat layer 53 of the substrate 50is no longer needed, the thickness between the display panel 20 and thecover layer 70 can be reduced even more.

<Display Device with Capacitive Touch Panel (Sixth Embodiment)>

FIG. 6(a) schematically illustrates a cross-sectional structure of themain part of a sixth display device with a capacitive touch panelaccording to the disclosure.

Here, the display device with a capacitive touch panel 600 illustratedin FIG. 6(a) differs from the example of the display device with acapacitive touch panel 400 as described previously in the followingpoints:

-   -   the polarizing plate 40 does not have the display panel-side        protective film 41, and the polarizing film 42 is positioned at        a surface (the lower surface in FIG. 6(a)) of the polarizing        plate 40 on the display panel 20 side;    -   the substrate 50 is bonded to a surface, on the display panel 20        side, of the polarizing film 42 of the polarizing plate 40;    -   another substrate 80 is further provided between the substrate        50 and the display panel 20;    -   the first conductive layer 61 is formed not on one surface (on        the display panel 20 side) of the substrate 50, but on one        surface (on the display panel 20 side) of said another substrate        80; and    -   the first conductive layer 61, the dielectric layer 62 formed on        a surface of the first conductive layer 61 on the display panel        20 side, and the second conductive layer 63 formed on a surface        of the dielectric layer 62 on the display panel 20 side are        positioned between said another substrate 80 and the display        panel 20.        The display device with a capacitive touch panel 600 has        otherwise the same features as the display device with a        capacitive touch panel 400.

Here, the bonding of the substrate 50 on the polarizing film 42 may beperformed by using a known adhesive layer or pressure sensitive adhesivelayer.

[Another Substrate]

In addition, said another substrate 80 is not particularly limited, andmay be a substrate that has a known optical film, a substrate that istransparent to visible light and does not cause any unnecessary phasedifference, or the like. Additionally, the formation of the firstconductive layer 61 on said another substrate 80 may be performed byusing the same method as used in the formation of the first conductivelayer 61 in the display device with a capacitive touch panel 400.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 400, the display device with acapacitive touch panel 600 can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel600 enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. In addition, in thedisplay device with a capacitive touch panel 600, the first conductivelayer 61, the dielectric layer 62, and the second conductive layer 63are all formed on said another substrate 80, there is no need to providetransparent base plates separately for forming the first and secondconductive layers. Accordingly, it is possible to simplify the structureof the touch sensor and reduce the number of members present between thedisplay panel 20 and the cover layer 70, thereby reducing the thicknessbetween the display panel 20 and the cover layer 70. As a result, areduction in thickness of the display device 600 can be achieved. It isnoted that since a conductive layer is formed on only one surface ofsaid another substrate 80 in the display device 600, a conductive layeruniform in thickness can be formed easily as compared to the case whereconductive layers are formed on both surfaces of said another substrate80.

In addition, in the display device with a capacitive touch panel 600,since the first conductive layer 61 is formed on said another substrate80 which is positioned closer to the display panel 20 than is thesubstrate 50 constituting the circularly polarizing plate, an indexmatching layer may not be provided on said another substrate 80 or thelike, as is the case with the aforementioned example of the displaydevice with a capacitive touch panel 400.

Moreover, in the display device 600, it is possible to cause thesubstrate 50 to function as a protective film for the polarizing film42, which may thus make the display panel-side protective film of thepolarizing plate 40 unnecessary, thereby reducing the thickness of thepolarizing plate 40. Accordingly, it is possible to further reduce thethickness between the display panel 20 and the cover layer 70.

Here, in the display device 600, the optical film 52 and the polarizingfilm 42 may be bonded together by using, as the substrate 50, asubstrate that does not have the hard coat layer 53 on the polarizingfilm 42 side of the optical film 52 (namely, a substrate having theoptical film 52 positioned at a surface thereof on the cover layer 70side). If not only the display panel-side protective film of thepolarizing plate 40, but also the hard coat layer 53 of the substrate 50is no longer needed, the thickness between the display panel 20 and thecover layer 70 can be reduced even more.

<Display Device with Capacitive Touch Panel (First Variation of SixthEmbodiment)>

FIG. 6(b) schematically illustrates a cross-sectional structure of themain part of a variation of the aforementioned display device with acapacitive touch panel 600.

Here, the display device with a capacitive touch panel 600A illustratedin FIG. 6(b) differs from the example of the display device with acapacitive touch panel 600 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the display panel 20 side) of said another substrate 80, but on        the other surface (on the cover layer 70 side) of said another        substrate 80; and    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the cover layer 70 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the cover layer 70 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between said another        substrate 80 and the substrate 50.        The display device with a capacitive touch panel 600A has        otherwise the same features as the display device with a        capacitive touch panel 600.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 600, the display device with acapacitive touch panel 600A can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel600A enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. It is also possible tosimplify the structure of the touch sensor and reduce the thicknessbetween the display panel 20 and the cover layer 70. Moreover, aconductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of saidanother substrate 80.

In addition, in the display device with a capacitive touch panel 600A,since the first conductive layer 61 is formed on said another substrate80 which is positioned closer to the display panel 20 than is thesubstrate 50, an index matching layer may not be provided on saidanother substrate 80 or the like, as is the case with the aforementionedexample of the display device with a capacitive touch panel 600.

Moreover, similar to the aforementioned example of the display devicewith a capacitive touch panel 600, the display device 600A can eliminatethe need for the display panel-side protective film of the polarizingplate 40 to reduce the thickness of the polarizing plate 40.Accordingly, it is possible to further reduce the thickness between thedisplay panel 20 and the cover layer 70.Here, in the display device 600A, a substrate that does not have thehard coat layer 53 on the polarizing film 42 side of the optical film 52may be used as the substrate 50 to further reduce the thickness betweenthe display panel 20 and the cover layer 70, as is the case with theaforementioned example of the display device with a capacitive touchpanel 600.

<Display Device with Capacitive Touch Panel (Seventh Embodiment)>

FIG. 7(a) schematically illustrates a cross-sectional structure of themain part of a seventh display device with a capacitive touch panelaccording to the disclosure.

Here, the display device with a capacitive touch panel 700 illustratedin FIG. 7(a) differs from the example of the display device with acapacitive touch panel 400 as described previously in the followingpoints:

-   -   the polarizing plate 40 does not have the display panel-side        protective film 41, and the polarizing film 42 is positioned at        a surface (the lower surface in FIG. 7(a)) of the polarizing        plate 40 on the display panel 20 side;    -   the display device 700 further comprises a polarizing plate-side        substrate 90 between the substrate 50 and the polarizing plate        40, more specifically between the substrate 50 and the        polarizing film 42 of the polarizing plate 40, and the substrate        50, the polarizing plate-side substrate 90, and the polarizing        plate 40 form a circularly polarizing plate;    -   the polarizing plate-side substrate 90 is bonded to a surface,        on the display panel 20 side, of the polarizing film 42 of the        polarizing plate 40;    -   the polarizing plate-side substrate 90 has another optical film        92 with a phase difference of λ/2; and    -   the slow axis of the optical film 52, a slow axis of said        another optical film 92, and the transmission axis of the        polarizing film 42 intersect at a predetermined angle.        The display device with a capacitive touch panel 700 has        otherwise the same features as the display device with a        capacitive touch panel 400.

Here, the bonding of the polarizing plate-side substrate 90 on thepolarizing film 42 may be performed by using a known adhesive layer orpressure sensitive adhesive layer.

[Polarizing Plate-Side Substrate]

The polarizing plate-side substrate 90 has said another optical film 92with a phase difference of λ/2 and hard coat layers 91, 93 formed onboth surfaces of the optical film 92. Additionally, said another opticalfilm 92 can be produced by using the same material and method as thoseused for the optical film 52, except that the phase difference to beimparted to light is set to λ/2.It is noted that in the display device with a capacitive touch panelaccording to the disclosure, the polarizing plate-side substrate 90 maynot have the hard coat layers 91, 93. In addition, similar to thesubstrate 50, the polarizing plate-side substrate 90 may have an opticalfunctional layer, such as an index matching layer and a low refractiveindex layer, instead of or in addition to the hard coat layers 91, 93.

As used herein, the phrase “with a phase difference of λ/2” indicatesthat the phase difference (retardation Re) to be applied to lighttransmitted through said another optical film 92 of the polarizingplate-side substrate 90 in the stacking direction is about one-half ofthe wavelength λ of the light. Specifically, in the case where thetransmitted light has a wavelength range from 400 nm to 700 nm, and whenRe is about one-half of the wavelength λ, it is meant that Re is in therange of λ/2±65 nm, preferably in the range of λ/2±30 nm, and morepreferably in the range of λ/2±10 nm. It is noted that Re is theretardation in the in-plane direction represented by the equationRe=(nx−ny)×d, where nx is the refractive index in the film plane in theslow axis direction, ny is the refractive index in a directionorthogonal, in the film plane, to the slow axis in the film plane, and dis the thickness of said another optical film 92.

In addition, the optical film 52 of the substrate 50 and said anotheroptical film 92 of the polarizing plate-side substrate 90 are used incombination to provide an optical plate that imparts a phase differenceof λ/4 (a so-called wideband quarter wavelength plate), and arepreferably formed from the same material having the same wavelengthdispersion characteristics. Moreover, the optical film 52 and saidanother optical film 92 are arranged so that the slow axis of theoptical film 52 intersects the transmission axis of the polarizing film42 of the polarizing plate 40, and the slow axis of said another opticalfilm 92 of the polarizing plate-side substrate 90 intersects thetransmission axis of the polarizing film 42 of the polarizing plate 40,at predetermined angles, respectively, as viewed in the stackingdirection.

In this case, “predetermined angles” represent angles at which awideband quarter wavelength plate can be formed, specifically angles atwhich linearly polarized light A traveling from the cover layer 80 sidethrough the polarizing plate 40 towards the display panel 20 side isconverted into circularly polarized light A after passing through saidanother optical film 92 and the optical film 52 sequentially, andreverse circularly polarized light B resulting from the circularlypolarized light A reflected at the display panel 20 is converted intoanother linearly polarized light B orthogonal to the linearly polarizedlight A after passing through the optical film 52 and said anotheroptical film 92 sequentially.

Specifically, if it is now assumed that said another optical film 92 andthe optical film 52 have the same wavelength dispersion characteristics,and that X° is an angle at which the slow axis of the optical film 52intersects the transmission axis of the polarizing film 42, and Y° is anangle at which the slow axis of said another optical film 92 of thepolarizing plate-side substrate 90 intersects the transmission axis ofthe polarizing film 42, “predetermined angles” represent angles at whichthe following equation holds: X−2Y=45°. More specifically, for example,possible combinations of “predetermined angles” include: (i) about 75°at which the slow axis of the optical film 52 intersects thetransmission axis of the polarizing film 42 and about 15° at which theslow axis of said another optical film 92 of the polarizing plate-sidesubstrate 90 intersects the transmission axis of the polarizing film 42,and (ii) about 90° at which the slow axis of the optical film 52intersects the transmission axis of the polarizing film 42 and about22.5° at which the slow axis of said another optical film 92 of thepolarizing plate-side substrate 90 intersects the transmission axis ofthe polarizing film 42.

As used herein, “about 75°” more specifically covers angles of 75°±5°,preferably 75°±3°, more preferably 75°±1°, and even more preferably75°±0.3°, “about 15°” more specifically covers angles of 15°±5°,preferably 15°±3°, more preferably 15°±1°, and even more preferably15°±0.3°, “about 90°” more specifically covers angles of 90°±5°,preferably 90°±3°, more preferably 90°±1°, and even more preferably90°±0.3°, and “about 22.5°” more specifically covers angles of 22.5°±5°,preferably 22.5°±3°, more preferably 22.5°±1°, and even more preferably22.5°±0.3°.

It is noted that in view of the fact that the laminate including thepolarizing plate 40 can be produced easily by a roll-to-roll process,the optical film 52 is preferably a vertical stretched film when formingan intersection angle of about 90° with the transmission axis of thepolarizing film 42, or the optical film 52 is preferably an obliquelystretched film when forming an intersection angle of about 75° with thetransmission axis of the polarizing film 42, and said another opticalfilm 92 is preferably an obliquely stretched film when forming anintersection angle of about 15° with the transmission axis of thepolarizing film 42, or said another optical film 92 is preferably anobliquely stretched film when forming an intersection angle of about22.5° with the transmission axis of the polarizing film 42.

Additionally, in the display device with a capacitive touch panel 700,the circularly polarizing plate formed by the polarizing plate 40, thepolarizing plate-side substrate 90, and the substrate 50 is arrangedbetween the cover layer 70 and the display panel 20, where thepolarizing plate 40 has the polarizing film 42, the polarizingplate-side substrate 90 has said another optical film 92 with apredetermined phase difference and being arranged at a predeterminedoptical axis angle, and the substrate 50 has the optical film 52 with apredetermined phase difference and being arranged at a predeterminedoptical axis angle. This arrangement allows for preventing reflectedlight of incident external light from making visual recognition of thedisplayed content difficult. Specifically, linearly polarized lighttraveling from the cover layer 70 side through the polarizing plate 40towards the display panel 20 side is converted into circularly polarizedlight by the wideband quarter wavelength plate formed by said anotheroptical film 92 of the polarizing plate-side substrate 90 and theoptical film 52 of the substrate 50, and reverse circularly polarizedlight resulting from the circularly polarized light reflected at thedisplay panel 20 is converted into another linearly polarized lightorthogonal to the linearly polarized light by the wideband quarterwavelength plate (said another optical film 92 of the polarizingplate-side substrate 90 and the optical film 52 of the substrate 50). Inthis way, it is possible to prevent, by the polarizing plate 40,transmission of said another linearly polarized light into the coverlayer 70 side. Therefore, the display device with a capacitive touchpanel 700 enables the operator to visually recognize the displayedcontent easily without interruption by reflected light.

In addition, in the display device with a capacitive touch panel 700,the first conductive layer 61, the dielectric layer 62, and the secondconductive layer 63 are all formed on the substrate 50 as theconductive-layer base member, there is no need to provide transparentbase plates separately for forming the first and second conductivelayers. Accordingly, it is possible to simplify the structure of thetouch sensor and reduce the number of members present between thedisplay panel 20 and the cover layer 70, thereby reducing the thicknessbetween the display panel 20 and the cover layer 70. As a result, areduction in thickness of the display device 700 can be achieved. It isnoted that since a conductive layer is formed on only one surface of thesubstrate 50 as the conductive-layer base member in the display device700, a conductive layer uniform in thickness can be formed easily ascompared to the case where conductive layers are formed on both surfacesof the substrate 50.

In the display device with a capacitive touch panel 700, since the firstconductive layer 61 is formed on the display panel 20 side of thesubstrate 50 constituting the circularly polarizing plate, an indexmatching layer may not be provided on the substrate 50.

Moreover, in the display device 700, it is possible to cause thepolarizing plate-side substrate 90 to function as a protective film forthe polarizing film 42, which may thus make the display panel-sideprotective film of the polarizing plate 40 unnecessary, thereby reducingthe thickness of the polarizing plate 40. Accordingly, it is possible tofurther reduce the thickness between the display panel 20 and the coverlayer 70.

Here, in the display device 700, said another optical film 92 and thepolarizing film 42 may be bonded together by using, as the polarizingplate-side substrate 90, a substrate that does not have the hard coatlayer 93 on the polarizing film 42 side of said another optical film 92(namely, a substrate having said another optical film 92 positioned at asurface thereof on the cover layer 70 side). If not only the displaypanel-side protective film of the polarizing plate 40, but also the hardcoat layer 93 of the polarizing plate-side substrate 90 is no longerneeded, the thickness between the display panel 20 and the cover layer70 can be reduced even more.

<Display Device with Capacitive Touch Panel (First Variation of SeventhEmbodiment)>

FIG. 7(b) schematically illustrates a cross-sectional structure of themain part of a variation of the aforementioned display device with acapacitive touch panel 700.

Here, the display device with a capacitive touch panel 700A illustratedin FIG. 7(b) differs from the example of the display device with acapacitive touch panel 700 as described previously in the followingpoints:

-   -   the first conductive layer 61 is formed not on one surface (on        the display panel 20 side) of the substrate 50 as the        conductive-layer base member, but on the other surface (on the        cover layer 70 side) of the substrate 50 as the conductive-layer        base member;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the cover layer 70 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the cover layer 70 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the substrate        50 and the polarizing plate-side substrate 90.        The display device with a capacitive touch panel 700A has        otherwise the same features as the display device with a        capacitive touch panel 700.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 700, the display device with acapacitive touch panel 700A can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel700A enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. It is also possible tosimplify the structure of the touch sensor and reduce the thicknessbetween the display panel 20 and the cover layer 70. Moreover, aconductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of thesubstrate 50 as the conductive-layer base member.

In addition, in the display device with a capacitive touch panel 700A,an index matching layer may not be provided on the substrate 50 or thelike, as is the case with the aforementioned example of the displaydevice with a capacitive touch panel 700.

Moreover, similar to the aforementioned example of the display devicewith a capacitive touch panel 700, the display device 700A can eliminatethe need for the display panel-side protective film of the polarizingplate 40 to reduce the thickness of the polarizing plate 40.

<Display Device with Capacitive Touch Panel (Second Variation of SeventhEmbodiment)>

FIG. 7(c) schematically illustrates a cross-sectional structure of themain part of another variation of the aforementioned display device witha capacitive touch panel 700.

Here, the display device with a capacitive touch panel 700B illustratedin FIG. 7(c) differs from the example of the display device with acapacitive touch panel 700 as described previously in the followingpoints:

-   -   the conductive-layer base member is not the substrate 50 but the        polarizing plate-side substrate 90, and the first conductive        layer 61 is formed on one surface (on the display panel 20 side)        of the polarizing plate-side substrate 90 as the        conductive-layer base member;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the display panel 20 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the display panel 20 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the substrate        50 and the polarizing plate-side substrate 90 as the        conductive-layer base member.        The display device with a capacitive touch panel 700B has        otherwise the same features as the display device with a        capacitive touch panel 700.

Here, the formation of the first conductive layer 61 on the polarizingplate-side substrate 90 may be performed by using the same method asused in the formation of the first conductive layer 61 in the displaydevice with a capacitive touch panel 400.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 700, the display device with acapacitive touch panel 700B can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel700B enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. It is also possible tosimplify the structure of the touch sensor and reduce the thicknessbetween the display panel 20 and the cover layer 70. It is noted thatsince a conductive layer is formed on only one surface of the polarizingplate-side substrate 90 as the conductive-layer base member in thedisplay device 700B, a conductive layer uniform in thickness can beformed easily as compared to the case where conductive layers are formedon both surfaces of the polarizing plate-side substrate 90.

In addition, in the display device with a capacitive touch panel 700B,since the first conductive layer 61 is formed on the display panel 20side of the polarizing plate-side substrate 90, an index matching layermay not be provided on the polarizing plate-side substrate 90 or thelike.

Moreover, similar to the aforementioned example of the display devicewith a capacitive touch panel 700, the display device 700B can eliminatethe need for the display panel-side protective film of the polarizingplate 40 to reduce the thickness of the polarizing plate 40.

<Display Device with Capacitive Touch Panel (Third Variation of SeventhEmbodiment)>

FIG. 7(d) schematically illustrates a cross-sectional structure of themain part of another variation of the aforementioned display device witha capacitive touch panel 700.

Here, the display device with a capacitive touch panel 700C illustratedin FIG. 7(d) differs from the example of the display device with acapacitive touch panel 700 as described previously in the followingpoints:

-   -   the conductive-layer base member is not the substrate 50 but the        polarizing plate 40, and the first conductive layer 61 is formed        on a surface, on the cover layer 70 side, of the polarizing        plate 40 as the conductive-layer base member, specifically on a        surface, on the cover layer 70 side, of the cover layer-side        protective film 43 of the polarizing plate 40;    -   the dielectric layer 62 is formed on a surface of the first        conductive layer 61 on the cover layer 70 side, and the second        conductive layer 63 is formed on a surface of the dielectric        layer 62 on the cover layer 70 side; and    -   the first conductive layer 61, the dielectric layer 62, and the        second conductive layer 63 are positioned between the cover        layer 70 and the polarizing plate 40 as the conductive-layer        base member.        The display device with a capacitive touch panel 700C has        otherwise the same features as the display device with a        capacitive touch panel 700.

Here, the formation of the first conductive layer 61 on the polarizingplate 40 may be performed by using the same method as used in theformation of the first conductive layer 61 in the display device with acapacitive touch panel 400.

Additionally, similar to the aforementioned example of the displaydevice with a capacitive touch panel 700, the display device with acapacitive touch panel 700C can prevent reflected light of incidentexternal light from making visual recognition of the displayed contentdifficult. Therefore, the display device with a capacitive touch panel700C enables the operator to visually recognize the displayed contenteasily without interruption by reflected light. It is also possible tosimplify the structure of the touch sensor and reduce the thicknessbetween the display panel 20 and the cover layer 70. It is noted thatsince a conductive layer is formed on only one surface of the polarizingplate 40 as the conductive-layer base member in the display device 700C,a conductive layer uniform in thickness can be formed easily as comparedto the case where conductive layers are formed on both surfaces of thepolarizing plate 40.

Moreover, similar to the aforementioned example of the display devicewith a capacitive touch panel 700, the display device 700C can eliminatethe need for the display panel-side protective film of the polarizingplate 40 to reduce the thickness of the polarizing plate 40.

Moreover, in the display device 700C, the first conductive layer 61,dielectric layer 62, and second conductive layer 63 constituting thecapacitive touch sensor are disposed closer to the cover layer 70 thanis the polarizing plate 40, specifically between the polarizing plate 40and the cover layer 70. Accordingly, it is possible to maintain asufficient distance, even in the device with a reduced thickness,between the display panel and the first conductive layer 61, dielectriclayer 62, and second conductive layer 63 constituting the touch sensor,as compared to the case where the first conductive layer 61, dielectriclayer 62, and second conductive layer 63 are provided closer to thedisplay panel 20 than is the polarizing plate 40. Consequently, it ispossible to suppress a decrease in sensitivity of the touch sensorcaused by the influence of electrical noise from the display panel 20side.

While examples of the display device with a capacitive touch panelaccording to the disclosure have been described above, the displaydevice with a capacitive touch panel according to the disclosure is notlimited to the above examples, but is capable of modifications as deemedappropriate.

INDUSTRIAL APPLICABILITY

According to the disclosure, it is possible to provide a display devicewith a capacitive touch panel that is reduced in thickness.

According to the disclosure, it is also possible to provide a displaydevice with a capacitive touch panel that can be operated by theoperator even through polarized sunglasses and is reduced in thickness.

Moreover, according to the disclosure, it is possible to provide adisplay device with a capacitive touch panel that can prevent reflectedlight of incident external light from making visual recognition of thedisplayed content difficult, and that is reduced in thickness.

REFERENCE SIGNS LIST

10 Backlight-side polarizing plate

20 Display panel

21 Thin film transistor base plate

22 Liquid crystal layer

23 Color filter base plate

24 Organic EL display (OLED) panel

25 Barrier layer

30 Phase difference film

40 Viewing-side polarizing plate, Polarizing plate

41 Display panel-side protective film

42 Polarizing film

43 Cover layer-side protective film

50 Substrate

51, 53 Hard coat layer

52 Optical film

61 First conductive layer

62 Dielectric layer

63 Second conductive layer

70 Cover layer

80 Another substrate

90 Polarizing plate-side substrate

91, 93 Hard coat layer

92 Another optical film

100, 100A, 100B Display device with a capacitive touch panel

200, 200A, 200B Display device with a capacitive touch panel

300, 300A Display device with a capacitive touch panel

400, 400A, 400B Display device with a capacitive touch panel

500, 500A, 500B Display device with a capacitive touch panel

600, 600A Display device with a capacitive touch panel

700, 700A, 700B, 700C Display device with a capacitive touch panel

The invention claimed is:
 1. A display device with a capacitive touchpanel comprising a laminate between a display panel and a cover layer,the laminate having a viewing-side polarizing plate, a first conductivelayer, a dielectric layer, a second conductive layer, and a substrate,the first conductive layer, the dielectric layer, and the secondconductive layer constituting a capacitive touch sensor, wherein thefirst conductive layer, the dielectric layer, the second conductivelayer, and the substrate are positioned closer to the cover layer thanis the viewing-side polarizing plate, the first conductive layer isformed on one surface of the substrate, the dielectric layer is formedon a surface of the first conductive layer opposite to the substrateside, the second conductive layer is formed on a surface of thedielectric layer opposite to the first conductive layer side, thesubstrate has an optical film with a phase difference of (2n−1)λ/4,where n is a positive integer, the viewing-side polarizing plate has apolarizing film, and a slow axis of the optical film intersects atransmission axis of the polarizing film at an angle of about 45° asviewed in a stacking direction.
 2. The display device with a capacitivetouch panel according to claim 1, wherein the first conductive layer isformed on a surface of the substrate on the side of the cover layer, thepolarizing film is positioned at a surface of the viewing-sidepolarizing plate on the side of the cover layer, and the substrate isbonded to a surface of the polarizing film on the side of the coverlayer.
 3. The display device with a capacitive touch panel according toclaim 1, wherein the display panel is a liquid crystal panel.
 4. Thedisplay device with a capacitive touch panel according to claim 1,wherein the optical film is an obliquely stretched film.
 5. The displaydevice with a capacitive touch panel according to claim 1, wherein theoptical film is formed from a cycloolefin polymer, polycarbonate,polyethylene terephthalate, or triacetyl cellulose.
 6. The displaydevice with a capacitive touch panel according to claim 1, wherein thefirst conductive layer and the second conductive layer are formed byusing indium tin oxide, carbon nanotubes, or silver nanowires.